Electric power storage module

Abstract

The electric power storage module (10) comprises: a plurality of electric power storage devices (20); a case (40) that holds a plurality of the electric power storage devices (20); a cooling liquid (50) that immerses a plurality of the electric power storage devices (20) in the case (40); and a positive electrode current collector plate (60) that connects the positive electrode terminals (26A) of the electric power storage devices (20) to each other. The positive electrode current collector plate (60) contains a residual part and a fuse link part (63) having a higher resistance than the residual part, and a heat insulation part is formed on the outer surface of the fuse link part (63).

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. 4788646

[0004] 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.

[0005] The energy storage module according to the present disclosure comprises a plurality of energy storage devices, a case in which the plurality of energy storage devices are housed, a coolant in which the plurality of energy storage devices are immersed within the case, and a current collector plate that connects the terminals of the plurality of energy storage devices to each other, wherein the current collector plate includes a remainder and a fuse link portion having a higher resistance than the remainder, and an insulating portion is formed on the outer surface of the fuse link portion.

[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 electricity storage module according to an embodiment of the present invention; FIG. 2 is a side cross-sectional view showing an electricity storage device according to the embodiment; FIG. 3 is a plan view showing a positive electrode current collector plate according to the 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] The configuration of an energy storage module 10 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] In the following, the components of the energy storage module 10 may be described using the axial, radial, or circumferential direction of a cylindrical energy storage device 20 (described later).

[0012] The energy storage module 10 includes a plurality of 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 positive current collector plate 60 serving as a first electrode current collector plate that connects positive terminals 26A serving as first electrode terminals of the energy storage devices 20, and a negative current collector plate 70 serving as a second electrode current collector plate that connects negative terminals 25C serving as second electrode terminals of the energy storage devices 20. In other words, the coolant 50 fills at least a portion of the gap (void) inside the case 40.

[0013] The multiple power storage devices 20 may be packed as densely as possible within the power storage module 10 while 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). Furthermore, the multiple power storage devices may be arranged such that the power storage devices closest to each other are located on all four sides.

[0014] [Power Storage Device] The power storage device 20 as an example of an embodiment will be described in detail with reference to FIG.

[0015] 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, etc. may also be used. The power storage device 20 includes an electrode group 24, for example, in which a strip-shaped positive electrode 21 and a strip-shaped negative electrode 22 are wound with a strip-shaped separator 23 interposed therebetween, a cylindrical outer can 25 that houses the electrode group 24 together with an electrolyte solution, a sealing body 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 and the sealing body 26, and a negative electrode tab 28 that electrically connects the negative electrode 22 and the outer can 25. An insulating gasket 29 may be disposed between the outer periphery of the sealing body 26 and the inner circumferential surface of the opening of the outer can 25.

[0016] 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.

[0017] The sealing body 26 may be provided with a current interrupter (CID) or an exhaust valve that ruptures when the pressure inside the outer can 25 reaches or exceeds a predetermined pressure. An insulating plate 30 for insulating the electrode group 24 from the outer can 25 may be provided between the electrode group 24 and the bottom surface of the outer can 25, or between the electrode group 24 and the protrusion (groove portion 25A). When the insulating plate 30 is provided, the positive electrode tab 27 may extend 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.

[0018] In the energy storage device 20, a positive electrode terminal 26A serving as a first electrode terminal is provided on the top surface of the sealing body 26, and a negative electrode terminal 25C serving as a second electrode terminal is provided on the bottom surface 25B of the outer can 25. In other words, a part of the sealing body 26 is the positive electrode terminal 26A, and a part of the bottom 25B is the negative electrode terminal 25C. A positive electrode lead 62 of a positive electrode current collector 60 is joined by welding to the top surface of the sealing body 26, which serves as the positive electrode terminal 26A serving as the first electrode terminal. A negative electrode lead 72 of a negative electrode current collector 70 is joined by welding to the bottom surface 25B of the outer can 25, which serves as the negative electrode terminal 25C serving as the second electrode terminal.

[0019] 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 thereof include polyethylene, polypropylene, polyamide, and ABS.

[0020] The lower side of the power storage device 20 is held by a lower holder 32. The lower holder 32 is made 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.

[0021] [Case] ​​The case 40 will be described again with reference to FIG.

[0022] As described above, the case 40 is a member that houses a plurality of power storage devices 20, and positive and negative current collector plates 60 and 70 (described later). The case 40 is made of a metal such as aluminum or a resin, and is formed into a substantially rectangular parallelepiped. The case 40 can protect the power storage devices 20 housed therein from dust and water.

[0023] [Coolant] The coolant 50 will be described with reference to FIG.

[0024] As described above, the coolant 50 is a liquid that immerses the multiple power storage devices 20, and the positive electrode current collector plates 60 and negative electrode current collector plates 70 described below, inside the case 40. 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. As the coolant 50, for example, insulating oil, transformer oil, silicone oil, a fluorine-based inert liquid such as hydrofluoroether, or the like may be used.

[0025] [Positive Electrode Current Collector Plate] The positive electrode current collector plate 60 will be described with reference to FIGS. 1 and 3. FIG.

[0026] As described above, the positive electrode current collector 60 is a member that connects the positive electrode terminals 26A, which serve as first electrode terminals, to each other. The positive electrode current collector 60 is disposed on the upper surface of the upper holder 31 inside the case 40 and is immersed in the coolant 50. The positive electrode current collector 60 is formed of a conductive metal plate. The positive electrode current collector 60 is formed of aluminum, for example. The positive electrode current collector 60 has an opening 61, a positive electrode lead 62, and a fuse link portion 63, each of which will be described in detail below.

[0027] Opening 61 is an opening formed corresponding to the top surface of sealing body 26 serving as positive electrode terminal 26A, which is the first electrode terminal of power storage device 20. Opening 61 is also formed corresponding to the opening of upper holder 31 that exposes the top surface of sealing body 26.

[0028] The positive electrode lead 62 is a portion that is joined by welding to the top surface of the sealing body 26 as a positive electrode terminal that is a first electrode terminal of the power storage device 20. The positive electrode lead 62 is formed in, for example, a rectangular shape in a plan view.

[0029] The fuse link portion 63 has a higher resistance than the rest of the positive current collector plate 60, and when an excessive current flows and the temperature reaches or exceeds a predetermined temperature (hereinafter referred to as the melting point temperature), the fuse link portion 63 melts to cut off the circuit of the positive current collector plate 60. The fuse link portion 63 can prevent other parallel-connected power storage devices 20 from short-circuiting when a thermal runaway occurs in one power storage device 20.

[0030] Here, the fuse link portion 63 functions as a current interruption device when the fuse link portion 63 reaches or exceeds its melting point and melts down. However, if the positive electrode current collector plate 60 is immersed in the coolant 50, the fuse link portion 63 is cooled, and it may take a long time for the fuse link portion 63 to reach its melting point, or there is a risk that the current will not be interrupted even with an excessive current that reaches the melting point.

[0031] Therefore, as will be described below, by applying a heat insulating treatment to only the positive current collector plate 60 or the fuse link portion 63 (in other words, by forming a heat insulating portion on the outer surface of the fuse link portion 63), it is possible to ensure the original current interruption performance even when the positive current collector plate 60 is immersed in the coolant 50. This makes it possible to improve the reliability of the electricity storage module 10.

[0032] [Anodizing] Anodizing may be performed as a heat insulating treatment on only the positive current collector 60 or the fuse link portion 63 (an oxide film may be formed as a heat insulating portion). More specifically, the positive current collector 60 is formed of aluminum, and an anodic oxide film is formed on the entire surface of the positive current collector 60 or only on the surface of the fuse link portion 63. To form the anodic oxide film, electrolysis may be performed using the positive current collector 60 as the anode in a treatment bath containing dilute sulfuric acid, oxalic acid, or the like. Note that when an oxide film is provided on the fuse link portion 63 as a heat insulating portion in this way, it can be said that an oxide film that is thicker or denser than the oxide film that naturally occurs on the rest of the positive current collector 60 is formed.

[0033] With the above configuration, even when the positive electrode current collector plate 60 is immersed in the coolant 50, the anodizing treatment improves the insulating performance of only the positive electrode current collector plate 60 or the fuse link portion 63, thereby ensuring the function of the fuse link portion 63 as a current interruption device.

[0034] In addition, when forming an anodized film only on the surface of the fuse link portion 63, the other parts of the positive electrode current collector 60 may be masked, and the positive electrode current collector 60 may be electrolyzed as the anode in a treatment bath of dilute sulfuric acid or oxalic acid or the like.

[0035] [Foam] A foam may be applied to the fuse link portion 63 as a heat insulating treatment (the heat insulating portion may contain a foam). The foam preferably has a property of generating bubbles when the fuse link portion 63 reaches a predetermined temperature or higher. The predetermined temperature is preferably lower than the melting temperature of the fuse link portion 63. The predetermined temperature is preferably lower than the boiling point of the coolant 50.

[0036] With the above configuration, even when the positive current collector plate 60 is immersed in the coolant 50, if an excessive current flows through the fuse link portion 63 and the fuse link portion 63 reaches a predetermined temperature or higher, bubbles are generated from the foam. At this time, the bubbles generated from the foam keep the coolant 50 away from the periphery of the fuse link portion 63 (preventing the coolant 50 from contacting the fuse link portion 63), reducing the thermal conductivity of the foam and improving the heat insulating performance of the fuse link portion 63, thereby ensuring the function of the fuse link portion 63 as a current interruption device.

[0037] Physical foaming agents may be used as the foam. Physical foaming agents are produced by dissolving a gas or supercritical fluid in a plastic under high pressure. Heating the agent reduces the agent's solubility, thereby generating bubbles.

[0038] As the foam, a thermal decomposition type foaming agent such as ADCA (azodicarbonamide), DPT (N,N'-dinitropentamethylenetetramine), OBSH (4,4'-oxybisbenzenesulfonylhydrazide), bicarbonate, carbonate, or the like, or a resin, rubber, paint, or the like containing these may be used.

[0039] [Negative Electrode Current Collector Plate] As described above, the negative electrode current collector plate 70 is a member that connects the negative electrode terminals 25C, which serve as second electrode terminals, to each other. The negative electrode current collector plate 70 is disposed on the lower surface of the lower holder 32 inside the case 40 and is immersed in the coolant 50. The negative electrode current collector plate 70 is formed of a conductive metal plate. A negative electrode lead 72 and a fuse link portion 73, which will be described later, are formed on the negative electrode current collector plate 70.

[0040] The negative electrode lead 72 is a portion joined by welding to the bottom surface 25B of the outer can 25 as the negative electrode terminal 25C, which is the second electrode terminal of the power storage device 20. The fuse link portion 73 is a portion that melts to break the circuit when an excessive current flows and exceeds its melting point. The fuse link portion 73 can prevent other power storage devices 20 connected in parallel from short-circuiting when a thermal runaway occurs in the power storage device 20.

[0041] As with the above-described positive current collector plate 60, by performing a heat insulating treatment (forming a heat insulating portion) only on the negative current collector plate 70 or the fuse link portion 73, it is possible to ensure the original function as a current interruption device even when the negative current collector plate 70 is immersed in the coolant 50. This improves the reliability of the energy storage module 10. As for the heat insulating treatment, as described above, only the negative current collector plate 70 or the fuse link portion 73 may be anodized (an oxide coating may be formed), or only the fuse link portion may be coated with a foam.

[0042] In addition, when the positive electrode terminal 26A as the first electrode terminal of the power storage device and the negative electrode terminal 25C as the second electrode terminal are disposed at the upper end portion of the power storage device in the axial direction, the current collector plates that connect the positive electrode terminals 26A to each other and the negative electrode terminals 25C to each other may be disposed only on the upper surface of the upper holder. Even in such a configuration, it is preferable that the heat insulating treatment described above is applied only to the current collector plates or the fuse link portions.

[0043] Summary The present disclosure is further described by the following embodiments.

[0044] Configuration 1: An electricity storage module comprising: a plurality of electricity storage devices; a case that houses the plurality of electricity storage devices; a coolant that immerses the plurality of electricity storage devices within the case; and a current collector plate that connects electrode terminals of the plurality of electricity storage devices to each other, wherein the current collector plate includes a remainder and a fuse link portion having a higher resistance than the remainder, and a heat insulating portion is formed on an outer surface of the fuse link portion.

[0045] Configuration 2: The energy storage module according to configuration 1, wherein the heat insulating portion includes an oxide coating.

[0046] Configuration 3: The energy storage module according to configuration 1, wherein the heat insulating section includes a foam.

[0047] Configuration 4: The energy storage module according to Configuration 3, wherein bubbles are generated in the foam when a portion of the current collecting plate reaches or exceeds a predetermined temperature, and the predetermined temperature is lower than a meltdown temperature of the portion of the current collecting plate.

[0048] Configuration 5: The electric storage module according to configuration 3 or 4, wherein the predetermined temperature is lower than the boiling point of the coolant.

[0049] Configuration 6: The energy storage module according to any one of configurations 1 to 5, wherein the fuse link portion of the current collector plate is a portion that melts when an excessive current flows and the temperature reaches or exceeds a predetermined temperature.

[0050] 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.

[0051] 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 25C Negative electrode terminal 26 Sealing body 26A Positive electrode terminal 27 Positive electrode tab 28 Negative electrode tab 29 Gasket 30 Insulating plate 31 Upper holder 32 Lower holder 40 Case 50 Coolant 60 Positive electrode current collector plate 61 Opening 62 Positive electrode lead 63 Fuse link portion 70 Negative electrode current collector plate 72 Negative electrode lead 73 Fuse link portion

Claims

1. An energy storage module comprising: a plurality of energy storage devices; a case in which the plurality of energy storage devices are housed; a cooling liquid in which the plurality of energy storage devices are immersed within the case; and a current collecting plate connecting terminals of the plurality of energy storage devices to each other, wherein the current collecting plate includes a remainder and a fuse link portion having a higher resistance than the remainder, and a heat insulating portion is formed on an outer surface of the fuse link portion.

2. The energy storage module according to claim 1, wherein the heat insulating portion includes an oxide coating.

3. The energy storage module according to claim 1, wherein the heat insulating section includes a foam.

4. A storage module according to claim 3, wherein air bubbles are generated in the foam when a part of the current collector plate reaches or exceeds a predetermined temperature, and the predetermined temperature is lower than the meltdown temperature of the part of the current collector plate.

5. The electric storage module according to claim 4, wherein the predetermined temperature is lower than the boiling point of the cooling liquid.

6. An energy storage module according to any one of claims 1 to 5, wherein the fuse link portion of the current collector plate is a portion that melts when an excessive current flows and the temperature reaches or exceeds a predetermined temperature.

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