Power storage module

Abstract

A power storage module (10) comprises: at least one power storage device (20); a holder (30) in which the at least one power storage device (20) is accommodated; a plurality of compartments (42) formed by partitioning the holder (40) with partition members (41) in the axial direction of the power storage device (20); and a cooling liquid (50) for immersing the at least one power storage device (20) in the compartments (42). At least one of the partition members (41) is provided at least above the center in the axial direction of the power storage device (20).

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 (for example, see Patent Document 1).

[0003] Patent No. 6256439

[0004] Here, there is a demand for further improvement in the reliability of the power storage module.

[0005] The energy storage module according to the present disclosure is characterized by comprising at least one energy storage device, a housing in which the at least one energy storage device is housed, a plurality of compartments in which the housing is divided in the axial direction of the energy storage device by partition members, and a cooling liquid in which the at least one energy storage device is immersed in the compartments.

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

[0007] 1 is a side cross-sectional view showing an electric storage module according to a first embodiment; FIG. 2 is a side cross-sectional view showing an electric storage device as an example of an embodiment; FIG. 3 is a side cross-sectional view showing an electric storage module according to a second embodiment; FIG. 4 is a side cross-sectional view showing an electric storage module according to a third 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] First Embodiment (Overall Configuration of Energy Storage Module) A power storage module 10 according to a first 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 holder 40 as a housing for holding and accommodating the plurality of energy storage devices 20, a plurality of compartments 42 (not shown, hereinafter collectively referred to as upper compartment 42A, middle compartment 42B, and lower compartment 42C) in which the holder 40 is divided in the axial direction of the energy storage device 20 by at least one partition member 41 (not shown, hereinafter collectively referred to as upper partition member 41A and lower partition member 41B), a coolant 50 in which the plurality of energy storage devices 20 are immersed in the compartment 42, a recovery path 60 that captures and recovers the coolant 50 contained in gas exhausted from the compartment 42 in the event of an abnormality in the energy storage device 20, and a case 70 that accommodates the holder 40 and the recovery path 60.

[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 the four sides are arranged. Details of the power storage device 20 will be described later. Note that the power storage module of the present disclosure may include only one power storage device 20.

[0013] As described above, the holder 40 serving as a housing holds and houses a plurality of power storage devices 20. The holder 40 is formed of, for example, a thermoplastic resin. Thermoplastic resins are broadly classified into general-purpose plastics and engineering plastics, and polyethylene, polypropylene, polyamide, ABS, etc. are used.

[0014] The holder 40 includes an upper holder 40A, a middle holder 40B arranged below the upper holder 40A, and a lower holder 40C arranged below the middle holder 40B. A positive electrode current collector may be arranged on the upper surface of the upper holder 40A. The positive electrode current collector is a member that connects positive electrode terminals serving as first electrode terminals of the power storage device 20 to each other. The positive electrode current collector is formed of a conductive metal plate. A negative electrode current collector may be arranged on the lower surface of the lower holder 40C. The negative electrode current collector is a member that connects negative electrode terminals serving as second electrode terminals of the power storage device 20 to each other. The negative electrode current collector is formed of a conductive metal plate. Both the positive electrode current collector and the negative electrode current collector may be arranged together at one end of the power storage device 20.

[0015] The holder 40 is divided into a plurality of compartments 42 in the axial direction of the power storage device 20 by partition members 41. The partition members 41 include an upper partition member 41A provided above the axial center of the power storage device 20 and a lower partition member 41B provided below the axial center of the power storage device 20. More specifically, the upper partition member 41A is provided at the boundary between the upper holder 40A and the middle holder 40B. The lower partition member 41B is provided at the boundary between the middle holder 40B and the lower holder 40C.

[0016] In the present embodiment, the partition member 41 is provided at the boundary between the upper holder 40A and the middle holder 40B or at the boundary between the middle holder 40B and the lower holder 40C of the holder 40, but the present disclosure is not limited to this. The partition member 41 may be provided at any position inside the holder 40. In the energy storage module of the present disclosure, the partition member 41 may be formed with a compartment 42 that includes the gasket 29 of each energy storage device 20 and a compartment 42 that does not include the gasket 29.

[0017] The compartments 42 include an upper compartment 42A, a middle compartment 42B disposed below the upper compartment 42A, and a lower compartment 42C disposed below the middle compartment 42B. The upper compartment 42A is separated by an upper partition member 41A in the upper holder 40A. The middle compartment 42B is separated by an upper partition member 41A and a lower partition member 41B in the middle holder 40B. The lower compartment 42C is separated by a lower partition member 41B in the lower holder 40C. The upper compartment 42A, the middle compartment 42B, and the lower compartment 42C are each filled with coolant 50.

[0018] With the above configuration, the coolant 50 in the middle section 42B, which cools the axial center portion of the power storage device 20 in the event of an abnormality in the power storage device 20, can be isolated from the coolant 50 in the upper section 42A, which cools the axial upper end portion of the power storage device 20 in which a gasket 29 (described later) is immersed. Note that an abnormality in the power storage device 20 also includes a thermal runaway event in the power storage device 20. This makes it less likely that the gasket 29 will melt due to the high-temperature coolant 50 in the event of thermal runaway in the power storage device 20, thereby reducing the risk of a short circuit in the power storage device 20. As a result, the reliability of the power storage module 10 can be improved. Furthermore, even if the gasket 29 of the power storage device 20 is disposed in an upper position in the power storage module 10, the thermal effect of the heated coolant 50 on the gasket 29 can be suppressed.

[0019] As described above, the coolant 50 immerses the plurality of power storage devices 20 in the compartment 42. In the power storage module 10, the power storage devices 20 can be cooled by the coolant 50. 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.

[0020] As described above, the recovery path 60 captures and recovers the coolant 50 contained in the gas discharged from the compartment 42 when an abnormality occurs in the power storage device 20. The recovery path 60 will be described in detail later.

[0021] As described above, the case 70 houses the holder 40 and the recovery path 60. The case 70 is made of a metal such as aluminum or a resin, and is formed into a substantially rectangular parallelepiped shape. The case 70 can protect the power storage device 20 housed therein from dust and water.

[0022] [Power Storage Device] The power storage device 20 as an example of an embodiment will be described with reference to FIG.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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 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 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.

[0027] [Recovery Path] The recovery path 60 will be described again with reference to FIG.

[0028] As described above, the recovery path 60 captures and recovers the coolant 50 contained in the gas exhausted from the compartment 42 when an abnormality occurs in the power storage device 20. As will be described in detail later, the recovery path 60 can minimize loss of the coolant 50 in the compartment 42. As a result, the power storage module 10 can improve its ability to prevent fire from spreading and fire from leaking from the power storage device 20. This can improve the reliability of the power storage module 10.

[0029] As described above, abnormalities in the power storage device 20 include thermal runaway of the power storage device 20. During thermal runaway of 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 discharged from the case 70. Furthermore, during thermal runaway of the power storage device 20, the coolant 50 becomes mist-like (atomized liquid) in a high-temperature, high-pressure environment and is discharged from the case 70. Note that in the power storage module of the present disclosure, the gas containing the coolant 50 discharged from the compartment 42 does not necessarily have to be due to heating of the power storage device 20 whose temperature has risen. It may also be due to the coolant 50 being heated by some other factor.

[0030] In other words, the gas in case 70 during thermal runaway of storage device 20 includes coolant 50 that evaporates when storage device 20 reaches a high temperature under a high-temperature and high-pressure environment, coolant 50 that becomes mist-like (atomized liquid) under a high-temperature and high-pressure environment, and other gases.

[0031] Recovery path 60 has an exhaust section 61 through which gas is exhausted from compartment 42, a detour path 62 that collects mist-like coolant 50 contained in the gas, and a recovery section 63 that recovers coolant 50 collected in detour path 62 into compartment 42. Exhaust section 61, detour path 62, and recovery section 63 are formed between case 70 and holder 40 and are in communication with each other.

[0032] Gas is exhausted from the compartment 42 to the exhaust section 61. Pressure release valves 64 (not shown, hereinafter collectively referred to as upper pressure release valve 64A, middle pressure release valve 64B, and lower pressure release valve 64C) are provided between the exhaust section 61 and the compartment 42. These valves exhaust only gas when the pressure in the compartment 42 is equal to or higher than a predetermined pressure. The pressure release valves 64 are preferably valves that can exhaust only gas, for example. The pressure release valves 64 may be made of a waterproof, breathable membrane, for example.

[0033] The pressure release valves 64 include an upper pressure release valve 64A, a middle pressure release valve 64B, and a lower pressure release valve 64C. The upper pressure release valve 64A is provided between the exhaust section 61 and the upper compartment 42A. The middle pressure release valve 64B is provided between the exhaust section 61 and the middle compartment 42B. The lower pressure release valve 64C is provided between the exhaust section 61 and the lower compartment 42C.

[0034] The detour 62 collects the coolant mist 50 contained in the gas. The detour 62 is formed as a path that detours upward. By moving the coolant mist 50 in a detour in the detour 62, the number of times the coolant mist 50 collides with the wall surface of the detour 62 is increased, causing the coolant mist 50 to condense. This allows the coolant mist 50 to be collected.

[0035] The detour 62 is provided with an inclined portion 62A that slopes downward toward the collection portion 63. The inclined portion 62A is provided at the top of the detour 62. The inclined portion 62A allows the condensed coolant 50 to flow downward by gravity.

[0036] A case exhaust valve 67 is provided on the upper surface of the top of the bypass 62. The case exhaust valve 67 exhausts gas from the holder 40 other than the mist of coolant 50 from the bypass 62.

[0037] The recovery unit 63 recovers the coolant 50 collected in the bypass 62 into the compartment 42. Between the recovery unit 63 and the compartment 42, there are provided on-off valves 65 (not shown; hereinafter, these are collectively referred to as upper on-off valve 65A, middle on-off valve 65B, and lower on-off valve 65C) that open when the liquid level of the coolant 50 filled in the compartment 42 is below a predetermined height. The on-off valves 65 may be, for example, damper-type on-off valves provided at the upper end of the opening. The predetermined liquid level may be the lower end position of the on-off valves 65. The on-off valves 65 allow the liquefied coolant 50 to be recovered into the compartment 42.

[0038] The on-off valves 65 include an upper on-off valve 65A, a middle on-off valve 65B, and a lower on-off valve 65C. The upper on-off valve 65A is provided between the collection section 63 and the upper compartment 42A. The middle on-off valve 65B is provided between the collection section 63 and the middle compartment 42B. The lower on-off valve 65C is provided between the collection section 63 and the lower compartment 42C.

[0039] Below the on-off valves 65, receivers 66 (not shown; hereinafter, a collective term for upper receiver 66A, middle receiver 66B, and lower receiver 66C) are provided in the collection section 63, protruding obliquely upward. The receivers 66 include upper receiver 66A, middle receiver 66B, and lower receiver 66C. The upper receiver 66A is provided below and adjacent to the upper on-off valve 65A. The middle receiver 66B is provided below and adjacent to the middle on-off valve 65B. The lower receiver 66C is provided below and adjacent to the lower on-off valve 65C. The receivers 66 enable efficient collection of the coolant 50 dropping down the collection section 63.

[0040] The protruding length of the receivers 66 increases from top to bottom. More specifically, the middle receiver 66B has a longer protruding length than the upper receiver 66A, and the lower receiver 66C has a longer protruding length than the middle receiver 66B. This allows the coolant 50 dropping down the collection section 63 to be collected evenly into the compartments 42.

[0041] Here, the energy storage module 10 will be described when the energy storage device 20 experiences thermal runaway. When the energy storage device 20 experiences thermal runaway, the energy storage device 20 may become hot. At this time, the axial center portion of the energy storage device 20 becomes hot, and part of the coolant 50 filled in the middle section 42B becomes mist-like in a high-temperature, high-pressure environment. As a result, the middle section 42B becomes high-pressure, the middle pressure release valve 64B is opened, and the mist-like coolant 50 is exhausted to the exhaust section 61.

[0042] The mist of coolant 50 exhausted to exhaust section 61 condenses as it passes through bypass 62 and flows along inclined section 62A of bypass 62 to collection section 63. The coolant 50 that has flowed to collection section 63 is collected in receiver 66. At this time, the liquid level is lowered in middle section 42B from which coolant 50 has been exhausted, so middle on-off valve 65B opens and the collected coolant 50 is collected. Note that the coolant 50 that has accumulated in upper receiver 66A and lower receiver 66C is not collected.

[0043] This minimizes loss of the coolant 50 inside the case 70. As a result, it is possible to enhance the function of preventing fire from spreading and fire from leaking from the power storage device 20 in the power storage module 10. This improves the reliability of the power storage module 10.

[0044] Second Embodiment A power storage module 110 according to a second embodiment will be described with reference to Fig. 3. In the following description, the same reference numerals will be used to designate components common to the power storage module 10 according to the first embodiment, and description thereof will be omitted.

[0045] In the energy storage module 110, the holder 40 is partitioned into a plurality of compartments 42 along the axial direction of the energy storage device 20 by only one partition member 41. The holder 40 also includes an upper holder 40A and a lower holder 40C disposed below the upper holder 40A. The partition member 41 is disposed above the axial center of the energy storage device 20 at the boundary between the upper holder 40A and the lower holder 40C. The upper compartment 42A is partitioned by the partition member 41 in the upper holder 40A. The lower compartment 42C is partitioned by a lower partition member 41B in the lower holder 40C.

[0046] According to the energy storage module 110, it is possible to separate the coolant 50 in the lower section 42C, which cools the axial central portion of the energy storage device 20 that becomes the hottest in the event of thermal runaway of the energy storage device 20, from the coolant 50 in the upper section 42A, which cools the axial upper end portion of the energy storage device 20 in which the gasket 29 is immersed. This makes it less likely that the gasket 29 will melt due to the high-temperature coolant 50 in the event of thermal runaway of the energy storage device 20, reducing the risk of short circuits in the energy storage device 20. As a result, it is possible to improve the reliability of the energy storage module 10.

[0047] Third Embodiment A power storage module 120 according to a third embodiment will be described with reference to Fig. 4. Note that, in the following, components common to the power storage module 10 according to the first embodiment described above will be denoted by the same reference numerals, and description thereof will be omitted.

[0048] The power storage module 120 includes a plurality of power storage devices 20, a coolant 50 in which the plurality of power storage devices 20 are immersed, and a case 70 as a housing for accommodating the power storage devices 20.

[0049] In the power storage module 120, the case 70 is divided into two compartments along the axial direction of the power storage device 20 by one partition member 71. The partition member 71 is disposed above the center of the power storage device 20 in the axial direction.

[0050] According to the energy storage module 120, the coolant 50 below the partition member 71 that cools the central portion of the energy storage device 20 in the axial direction, which becomes the hottest in the event of thermal runaway of the energy storage device 20, can be separated from the coolant 50 above the partition member 71 in which the gasket 29 of the energy storage device 20 is immersed. This makes it less likely that the gasket 29 will melt due to the high-temperature coolant 50 in the event of thermal runaway of the energy storage device 20, reducing the risk of short circuits in the energy storage device 20. As a result, the reliability of the energy storage module 10 can be improved. [Summary] The present disclosure will be further described with reference to the following embodiments. Configuration 1: An energy storage module comprising: at least one energy storage device; a housing that houses the at least one energy storage device; a plurality of compartments formed by dividing the housing in the axial direction of the energy storage device by partition members; and coolant in which the at least one energy storage device is immersed in the compartment. Configuration 2: The energy storage module according to configuration 1, wherein at least one partition member is provided at least above the axial center of the energy storage device.Configuration 3: The energy storage module according to configuration 2, wherein the at least one partition member is a plurality of the partition members, and one of the plurality of partition members is provided at least below the axial center of the energy storage device.Configuration 4: The energy storage module according to any one of configurations 1 to 3, wherein the housing is a holder that holds the plurality of energy storage devices, and further comprises: a recovery path that collects and recovers the coolant contained in gas exhausted from the compartment; and a case that houses the holder and the recovery path.Configuration 5: The energy storage module according to configuration 4, wherein the recovery path has an exhaust section through which the gas is exhausted from the compartment, a detour path that collects the coolant contained in the gas, and a recovery section that recovers the coolant collected in the detour path and returns it to the compartment. Configuration 6: The energy storage module according to Configuration 5, further comprising a pressure release valve disposed between the exhaust section and the compartment, the pressure release valve configured to exhaust only the gas when the pressure in the compartment is equal to or greater than a predetermined pressure.Configuration 7: The energy storage module according to configuration 5 or 6, wherein the detouring section is provided with an inclined section that slopes downward toward the recovery section.Configuration 8: The energy storage module according to any of configurations 5 to 7, wherein an on-off valve that opens when the liquid level of the coolant filled in the compartment is below a predetermined height is provided between the exhaust section and the compartment.Configuration 9: The energy storage module according to configuration 8, wherein a receiver that protrudes obliquely upward in the recovery section is provided below the on-off valve.Configuration 10: The energy storage module according to configuration 9, wherein the protruding length of the receiver increases from top to bottom.

[0051] 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.

[0052] 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, 40 Holder (housing of first embodiment), 40A Upper holder, 40B Middle holder, 40C Lower holder, 41 Partition member, 41A Partition member, 41B Partition member, 42 Compartment, 42A Upper compartment, 42B Middle compartment, 42C Lower compartment, 50 Coolant, 60 Recovery path, 61 Exhaust section, 62 Bypass route, 62A Inclined section, 63 Recovery section, 64 Pressure release valve, 64A Upper pressure release valve, 64B Middle pressure release valve, 64C Lower pressure release valve, 65 on / off valve, 65A upper on / off valve, 65B middle on / off valve, 65C lower on / off valve, 66 receiver, 66A upper receiver, 66B middle receiver, 66C lower receiver, 67 case exhaust valve, 70 case (housing of second embodiment), 71 partition member, 72 compartment, 110 power storage module, 120 power storage module

Claims

1. An energy storage module comprising: at least one energy storage device; a housing that houses the at least one energy storage device; a plurality of compartments formed by dividing the housing in the axial direction of the energy storage device by partition members; and a coolant in which the at least one energy storage device is immersed in the compartments.

2. The energy storage module according to claim 1, wherein at least one of the partition members is provided at least above the axial center of the energy storage device.

3. An energy storage module according to claim 2, wherein the at least one partition member is a plurality of partition members, and one of the plurality of partition members is provided at least below the axial center of the energy storage device.

4. An energy storage module according to any one of claims 1 to 3, wherein the housing is a holder for holding a plurality of the energy storage devices, and further comprises: a recovery path for capturing and recovering the coolant contained in the gas exhausted from the compartment; and a case for accommodating the holder and the recovery path.

5. An electric storage module according to claim 4, wherein the recovery path has an exhaust section through which the gas is exhausted from the compartment, a detour path that collects the cooling liquid contained in the gas, and a recovery section that recovers the cooling liquid collected in the detour path into the compartment.

6. An electricity storage module according to claim 5, wherein a pressure release valve is provided between the exhaust section and the compartment, for exhausting only the gas when the pressure in the compartment is equal to or greater than a predetermined pressure.

7. The energy storage module according to claim 5 or 6, wherein the detour path is provided with an inclined portion that slopes downward toward the recovery portion.

8. An energy storage module according to any one of claims 5 to 7, wherein an on-off valve is provided between the recovery section and the compartment, and opens when the liquid level of the cooling liquid filled in the compartment is below a predetermined height.

9. The energy storage module according to claim 8, wherein a receiver that protrudes obliquely upward in the recovery section is provided below the on-off valve.

10. The energy storage module according to claim 9, wherein the protruding length of the receiver increases from top to bottom.

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