Energy storage module

Abstract

This power storage module comprises: at least one cylindrical power storage device; and a lower holder that holds the lower end part of the power storage device, wherein on one of the surface facing the holding part of the power storage device and the surface facing the power storage device of the holding part, at least one recess is formed, and on the other, at least one projection that fits in the recess is formed.

Description

Technical Field

[0001] The present disclosure relates to an electricity storage module including at least one electricity storage device.

Background Art

[0002] Conventionally, electricity storage modules including at least one electricity storage device have been widely known. For example, Patent Document 1 discloses an electricity storage module molded by filling a resin between a plurality of electricity storage devices.

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] An electricity storage module including a plurality of electricity storage devices is sometimes used as a power source for motive power. An electricity storage module used as a power source for motive power is used in an environment where vibration occurs for a long time, and ensuring the reliability of fixing the electricity storage devices is a problem.

[0005] An object of the present disclosure is to provide an electricity storage module capable of firmly fixing an electricity storage device in a holder.

Means for Solving the Problem

[0006] The electricity storage module according to one aspect of the present disclosure includes at least one cylindrical electricity storage device, and a first holder that holds one end of the electricity storage device, wherein at least one recess is formed on one of a surface of the electricity storage device facing the first holder and a surface of the first holder facing the electricity storage device, and at least one protrusion that fits into the recess is formed on the other.

Effect of the Invention

[0007] According to one aspect of this disclosure, it is possible to provide an energy storage module that can firmly fix an energy storage device within a holder. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram showing the energy storage module of Embodiment 1. [Figure 2] This is a perspective view showing an example of a protrusion formed on the bottom of the energy storage device of Embodiment 1. [Figure 3] This is a schematic diagram showing the exhaust operation of high-temperature gas in the energy storage device of Embodiment 1. [Figure 4] This is a perspective view showing another example of a protrusion formed on the bottom of the energy storage device of Embodiment 1. [Figure 5] This is a schematic diagram showing the energy storage module of Embodiment 2. [Figure 6] This is a schematic diagram showing the energy storage module of Embodiment 3. [Figure 7] This is a schematic diagram showing the energy storage module of Embodiment 4. [Modes for carrying out the invention]

[0009] Embodiments of this disclosure will be described below with reference to the drawings. The shapes, materials, and quantities described below are illustrative examples and can be modified as appropriate depending on the specifications of the energy storage module. In all drawings below, equivalent elements will be denoted by the same reference numerals.

[0010] The energy storage module 10 of Embodiment 1 will be described using Figure 1. Figure 1 is a schematic diagram showing the energy storage module 10.

[0011] The energy storage module 10 is primarily used as a power source. For example, the energy storage module 10 is used as a power source for motor-driven electric equipment such as power tools, electric automobiles, electric assist bicycles, electric motorcycles, electric wheelchairs, electric tricycles, or electric carts. However, the use of the energy storage module 10 is not limited, and it may also be used as a power source for electrical equipment other than electric equipment, such as various electrical devices used indoors and outdoors, such as cleaners, radios, lighting devices, digital cameras, or video cameras.

[0012] The energy storage module 10 of Embodiment 1 comprises a plurality of cylindrical energy storage devices 50, a lower holder 11 as a first holder that holds the lower ends of each of the plurality of energy storage devices 50, and an upper holder 12 as a second holder that holds the upper ends of each of the plurality of energy storage devices 50. A holding portion 13 is provided between the energy storage devices 50 and the lower holder 11. Note that the first holder may also include the holding portion 13.

[0013] The energy storage device 50 uses a cylindrical lithium-ion secondary battery. However, the energy storage device 50 may also be a nickel-metal hydride battery or a capacitor. Multiple energy storage devices 50 are packed as tightly as possible within the energy storage module 10, and adjacent energy storage devices 50 are arranged in close proximity to each other. The energy storage device 50 includes an electrode body 55 including a positive electrode and a negative electrode, an outer casing 51 which is a case having a cylindrical tube portion, a bottom portion 51B formed at the lower end of the tube portion, and an opening formed at the upper end, and a sealing body 52 which seals the opening of the outer casing 51 in an insulated state from the outer casing 51. In the energy storage device 50, the positive electrode of the electrode body and the sealing body 52 are electrically connected, and the negative electrode and the outer casing 51 are electrically connected. In the energy storage device 50, the top plate of the sealing body 52 is configured as the positive electrode terminal. Also, in the energy storage device 50, the outer casing 51 is configured as the negative electrode terminal.

[0014] The upper holder 12 holds the upper ends of each of the multiple energy storage devices 50. The lower surface of the upper holder 12 has a housing portion that accommodates the upper ends of the energy storage devices 50. The upper holder 12 is made of an insulating material such as a thermoplastic resin or a thermosetting resin. The housing portion of the upper holder 12 may have an opening, exposing the positive and negative terminals.

[0015] A positive electrode current collector 61, connected to the positive electrode terminal, is positioned above the upper holder 12. A negative electrode current collector 62, connected to the negative electrode terminal, is also positioned above the upper holder 12. The positive electrode current collector 61 and the negative electrode current collector 62 are made of materials with good electrical and thermal conductivity, preferably metal plates such as iron, nickel, copper, or aluminum, with a nickel-plated surface. While the positive electrode current collector 61 and the negative electrode current collector 62 are arranged to overlap each other as shown in Figure 1, the configuration is not limited to this. For example, multiple current collectors may be arranged on the upper holder 12 at predetermined intervals, and each current collector may be connected in parallel or in series to multiple energy storage devices 50.

[0016] The lower holder 11 holds the lower ends of each of the multiple energy storage devices 50. The upper surface of the lower holder 11 has a housing portion that accommodates the lower ends of the energy storage devices 50. The lower holder 11 is made of an insulating material such as a thermoplastic resin or thermosetting resin. A holding portion 13 is provided between the housing portion of the lower holder 11 and the lower ends of the energy storage devices 50.

[0017] The holding part 13 is filled between the energy storage device 50 and the lower holder 11. The holding part 13 is preferably sealed with an epoxy adhesive or a silicone-based elastic adhesive. An epoxy adhesive is an adhesive that uses a resin containing epoxy groups (oxirane rings). Epoxy adhesives are generally two-component systems, with the main component being a substance containing epoxy groups. The curing agent also takes the form of an amine, ether, or ester containing epoxy groups, and the two components are mixed to form an epoxy adhesive through a chemical reaction. On the other hand, an elastic adhesive is an adhesive whose cured product is a rubbery elastic material.

[0018] A potting material can also be used as the holding portion 13. A transparent polyurethane resin obtained by chemically reacting two liquids, namely polyol as a main agent and isocyanate as a curing agent, is preferably used as the potting material. The protective material B is not limited to polyurethane resin, and urethane resin, epoxy resin, acrylic resin, UV curable resin or the like may also be used. In particular, when a material having rigidity after manufacturing the electricity storage module, such as a potting material, is used for the holding portion, only the holding portion may be used as the lower holder.

[0019] In an outer can 51 constituting the electricity storage device 50, a concave shape or a convex shape is formed on the surface facing the holding portion 13. In the outer can 51 illustrated in FIG. 1, a convex portion 51C is formed on a bottom portion 51B of the outer can 51.

[0020] In the holding portion 13, a concave shape or a convex shape is formed at a portion facing the bottom portion 51B of the outer can 51. When a convex shape is formed on the outer can 51, a concave shape is formed on the holding portion 13. When a concave shape is formed on the outer can 51, a convex shape is formed on the holding portion 13. The convex shape or concave shape formed on the outer can 51 and the convex shape or concave shape formed on the holding portion 13 are respectively formed so as to fit with each other. A convex shape or a concave shape may also be provided on the surface of the lower holder 11 facing the holding portion 13, similarly to the outer can 51, to increase the fixing strength of the holding portion 13 to the lower holder 11. At this time, the convex portion or concave portion of the outer can 51 does not need to face the convex shape or concave shape of the lower holder 11. A convex shape may be formed on the outer can 51, and a convex shape may also be formed on the lower holder 11.

[0021] An example of the convex portion 51C will be described with reference to FIG. 2. FIG. 2 is a perspective view showing the bottom portion 51B of the outer can 51 where the convex portion 51C is formed.

[0022] As described above, in the energy storage device 50, a protrusion 51C is formed on the bottom 51B of the outer casing 51. The protrusion 51C illustrated in Figure 2 is formed with a non-annular side surface. Specifically, in a plan view, the protrusion 51C has a shape that integrates a roughly circular shape and elongated oval shapes protruding from the outside of the roughly circular shape at 120° intervals. As described above, in the holding part 13, a recess 13C is formed on the surface facing the bottom 51B of the outer casing 51, which fits with the protrusion 51C illustrated in Figure 2. The lower end surface of the protrusion 51C may also be polygonal.

[0023] The effects of the protrusions 51C and recesses 13C will now be explained. The protrusions 51C and recesses 13C act as anchors on the holding part 13. The anchoring effect is the effect in which, during fixing, the holding part 13 penetrates into the irregularities of the material surface like tree roots and hardens, thereby increasing the fixing force. This is because the fixing force increases due to friction as the contact area between the outer can 51 and the holding part 13 increases, and the protrusions 51C and recesses 13C act as wedges when the energy storage device 50 tries to rotate within the holding part 13 (and consequently the lower holder 11). This makes it easier to restrict the position of the bottom 51B of the outer can 51 and the holding part 13 (and consequently the lower holder 11). In other words, the relationship between the energy storage device 50 and the holding part 13 can be made stronger. In particular, when the holding portion 13 (or the lower holder 11 that directly contacts the outer can 51 if the holding portion 13 is not provided) is molded by impregnating the energy storage device 50 with a viscous material and then hardening this viscous material, it is difficult to place an adhesive or other member to fix the energy storage device 50 between the molded holding portion 13 and the outer can 51. Therefore, it is possible to increase the fixing force of the energy storage device 50 within the lower holder 11 (including the holding portion 13) with a simple operation.

[0024] The protrusion 51C formed on the bottom 51B of the outer can 51 and the recess 13C formed on the holding portion 13 and engaged with the protrusion 51C act as an anchoring effect against rotational vibrations of the energy storage device 50, particularly in the lower holder 11. The protrusion (or recess) formed on the outer can 51 of this disclosure may have further protrusions or recesses formed on its outer circumferential surface (or inner circumferential surface in the case of a recess) to improve the reliability of the vertical alignment with respect to the holding portion 13 (and consequently the lower holder 11).

[0025] For example, a convex shape may be formed on the side surface of the outer can 51 in the portion facing the holding portion 13. In this case, a concave shape will be formed on the portion of the holding portion 13 facing the side surface of the outer can 51. Even in this case, the convex shape of the outer can 51 and the concave shape of the holding portion 13 will fit together. As a result, the convex portion formed on the side surface of the outer can 51 and the concave portion formed on the holding portion 13 that fits with the convex portion act as an anchoring effect, particularly against vertical vibrations of the energy storage device 50 in the lower holder 11.

[0026] The exhaust operation of the high-temperature gas from the energy storage device 50 will be explained using Figure 3. Figure 3 is a schematic diagram showing a cross-section of the energy storage device 50 using the outer casing 51 of Figure 2, cut along the cutting line BB.

[0027] The energy storage device 50 houses an electrode body 55 and an electrolyte. The electrode body 55 includes a positive electrode 56, a negative electrode 57, and a separator 58 interposed between the positive electrode 56 and the negative electrode 57, and has a wound structure in which the positive electrode 56 and the negative electrode 57 are wound around each other via the separator 58. An insulating plate 59 is also placed below the electrode body 55.

[0028] In the event of an abnormality, for example, if the positive electrode 56 and the negative electrode 57 are short-circuited, a very large current flows through the short-circuited area, generating a large amount of heat. Subsequently, the positive electrode 56 or the negative electrode 57 reacts with the electrolyte, generating a high-temperature gas.

[0029] As described above, in the energy storage device 50, a protrusion 51C is formed on the bottom 51B of the outer casing 51. The inner surface of the bottom 51B illustrated in Figure 3 is formed with a recess in the area corresponding to the protrusion 51C. Furthermore, the protrusion 51C of the bottom 51B illustrated in Figure 3 extends along the radial direction of the bottom 51B.

[0030] In the energy storage device 50 illustrated in Figure 3, compared to an energy storage device 50 in which a solid protrusion is formed on the outer casing 51, the high-temperature gas generated inside the outer casing 51 passes through the space R1 formed on the inner surface side of the protrusion 51C and is discharged to the top of the outer casing 51 from the space formed on the axial portion of the electrode body 55. The high-temperature gas is released to the outside by rupturing a part of the sealing body 52. ​​As a result, in the event of an abnormality, if high-temperature gas is generated inside the energy storage device 50, the high-temperature gas will be smoothly exhausted from the energy storage device 50. At this time, if the protrusion 51C that forms the space R1 has a region that overlaps with the center of the bottom 51B of the outer casing 51, as shown in Figures 2 and 3, the exhaust efficiency will be further increased. It is thought that similar effects can be obtained if a recess that has an anchoring effect to the holding portion 13 is formed at the bottom of the outer casing 51, and this recess is formed to extend in the radial direction of the bottom.

[0031] Another example of the protrusion 51C will be explained using Figure 4. Figure 4 is a perspective view showing the bottom 51B of the outer can 51 on which the protrusion 51C is formed.

[0032] Multiple protrusions 51C are formed (for example, four in the illustration). The protrusions 51C are approximately cylindrical in shape. Furthermore, the protrusions 51C are positioned on the bottom 51B in a location that does not coincide with the central axis P of the outer can 51. As described above, on the holding portion 13, only a few recesses 13C are formed on the surface of the outer can 51 facing the bottom 51B, which engage with the protrusions 51C (not shown).

[0033] In this alternative example of the convex portion 51C and concave portion 13C, the convex portion 51C and concave portion 13C act as anchors to the holding portion 13. This makes it easier to align the bottom portion 51B of the outer can 51 with the lower holder 11. In other words, the fixing of the energy storage device 50 with the holding portion 13 and, consequently, with the lower holder 11 can be strengthened.

[0034] The energy storage module 20 of Embodiment 2 will be described using Figure 5. Figure 5 is a schematic diagram showing the energy storage module 20.

[0035] The energy storage module 20 of Embodiment 2 comprises a plurality of cylindrical energy storage devices 50, a lower holder 21 as a first holder that holds the lower ends of each of the plurality of energy storage devices 50, and an upper holder 22 as a second holder that holds the upper ends of each of the plurality of energy storage devices 50. The energy storage devices 50 have the same configuration as the energy storage device 50 of Embodiment 1 described above, so their description is omitted.

[0036] The upper holder 22 is formed by hardening a potting material and holds the upper ends of each of the multiple energy storage devices 50. A housing portion 22A is formed on the lower surface of the upper holder 22, into which the upper ends of the energy storage devices 50 are fitted. In the housing portion 22A, the portion facing the sealing body 52 of the energy storage device 50 is made into a thin-walled portion 22B. The thin-walled portion 22B is formed to be sufficiently thinner than the other parts of the housing portion 22A. Preferably, the thin-walled portion 22B is, for example, 2 mm or less.

[0037] When forming the thin-walled portion 22B on the upper holder 22, when manufacturing the upper holder 22, a rod is placed at a predetermined distance from the sealing body 52 of the energy storage device 50, and potting material is filled and hardened. After the rod is hardened, the rod is removed to form the thin-walled portion 22B having a thickness equal to the distance between the rods. When a positive electrode current collector 61 or a negative electrode current collector 62 is placed on the upper part of the upper holder 22, the upper holder 22 is manufactured after joining these current collectors to the multiple energy storage devices 50.

[0038] The thin-walled portion 22B can cover the energy storage device 50 when it is in a normal state, thereby insulating the energy storage device 50 from the outside of the module. It also prevents foreign matter from entering the housing and, consequently, the energy storage device. Furthermore, an exhaust valve is provided in the sealing body 52, and if the energy storage device 50 enters an abnormal state, the exhaust valve will activate, and the force of the high-temperature gas ejected from the exhaust valve will destroy the thin-walled portion 22B, allowing the gas to be exhausted outside the energy storage module.

[0039] The energy storage module 30 of Embodiment 3 will be described using Figure 6. Figure 6 is a schematic diagram showing the energy storage module 30.

[0040] The energy storage module 30 of Embodiment 3 comprises a plurality of cylindrical energy storage devices 50, a lower holder 31 as a first holder that holds the lower ends of each of the plurality of energy storage devices 50, and an upper holder 32 as a second holder that holds the upper ends of each of the plurality of energy storage devices 50. In addition, in the energy storage module 30, protective material B is filled into the gaps between adjacent energy storage devices 50 as a potting process.

[0041] The energy storage device 50 includes an outer can 51 as a case having a cylindrical tube portion, a bottom portion 51B formed at the lower end of the tube portion, and an opening formed at the upper end, and a sealing body 52 that seals the opening. The outer can 51 has a grooved portion 51A that supports the sealing body 52, for example, formed on the side portion from the outside by rolling. The grooved portion 51A is preferably formed in an annular shape along the circumferential direction of the outer can 51, and its upper surface supports the sealing body 52. ​​Protective material B, which is filled in the gaps between adjacent energy storage devices 50, flows into the grooved portion 51A.

[0042] The protective material B used in potting is preferably a transparent polyurethane resin obtained by chemically reacting two liquids: a polyol as the main component and an isocyanate as a curing agent. Protective material B is not limited to polyurethane resin; urethane resin, epoxy resin, acrylic resin, etc., may also be used.

[0043] The effects of the energy storage module 30 of Embodiment 3 will now be described. The energy storage module 30 allows the energy storage device 50 to be firmly fixed. That is, the protective material B flows into the space R2 and the grooved portion 51A as an adhesive and acts as an anchoring effect. As a result, the energy storage device 50 can be firmly fixed to the upper holder 32.

[0044] The energy storage module 40 of Embodiment 4 will be described using Figure 7. Figure 7 is a plan cross-sectional view showing the energy storage module 40.

[0045] The energy storage module 40 of Embodiment 4 comprises a plurality of cylindrical energy storage devices 50 (three in the example shown in Figure 7), a lower holder (not shown) as a first holder that holds the lower ends of each of the plurality of energy storage devices 50, and an upper holder 42 (not shown) as a second holder that holds the upper ends of each of the plurality of energy storage devices 50. In addition, in the energy storage module 40, protective material B is filled into the gaps between adjacent energy storage devices 50 as a potting process. The energy storage devices 50 and protective material B have the same configuration as the energy storage device 50 of Embodiment 1 described above, so their description is omitted.

[0046] The upper holder 42 has a housing portion 42A into which the upper end of the energy storage device 50 is fitted. The housing portion 42A has an opening 42C that exposes a part of the sealing body 52 and a notch 42D that exposes the side surface of the energy storage device 50. In a plan view, the notch 42D is located in a position that does not interpose between an adjacent pair of batteries.

[0047] In the gap between adjacent energy storage devices 50, a void BV is formed vertically along the side surface of the energy storage device 50 below the notch 42D, where the protective material B is not filled. The void BV is formed in communication with the notch 42D. As a method for forming the void BV, for example, a rod-shaped jig may be inserted into the part where the void BV is to be formed when filling with the protective material B, and the jig may be removed after the protective material B has hardened.

[0048] In the energy storage device 50, thermal runaway may occur, causing the outer casing 51 to rupture and releasing high-temperature gas. According to the energy storage module 40, even if thermal runaway occurs in one energy storage device 50, the high-temperature gas will escape to the outside by rupturing the outer surface of the outer casing 51 exposed through the brittle and low-heat-capacity notch 42D. This suppresses the adverse effects of the high-temperature gas on energy storage devices 50 adjacent to the energy storage device 50 experiencing thermal runaway.

[0049] It should be noted that the present invention is not limited to the embodiments and their modifications described above, and various changes and improvements are possible within the scope of the claims of this application. [Explanation of Symbols]

[0050] 10 Energy storage module, 11 Lower holder, 13C Recess, 12 Upper holder, 13 Holding part, 50 Energy storage device, 51 Outer casing, 51A Grooved part, 51B Bottom part, 51C Protrusion, 52 Sealing body, 55 Electrode body, 56 Positive electrode, 57 Negative electrode, 58 Separator, 59 Insulating plate, 61 Positive electrode current collector, 62 Negative electrode current collector.

Claims

1. A plurality of cylindrical energy storage devices arranged in a first direction, In the aforementioned plurality of energy storage devices, a first holder having insulating properties holds one end in a second direction perpendicular to the first direction, A current collector plate is positioned on the other end side in the second direction of the plurality of energy storage devices and electrically connects the plurality of energy storage devices, Equipped with, On one of the insulating surfaces of each of the plurality of energy storage devices facing the first holder and the surface of the first holder facing the energy storage device, at least one recess is formed, and on the other, at least one protrusion is formed that fits into the recess. The outer circumferential surface of the convex portion and the inner circumferential surface of the concave portion overlap in the circumferential direction of the energy storage device. The aforementioned protrusions or recesses are formed in multiple locations, extending in the radial direction of the energy storage device. The plurality of protrusions or recesses are connected to each other at the radial center. Energy storage module.

2. The energy storage module according to claim 1, The energy storage device comprises a case having a cylindrical tube portion, a bottom portion provided at one end of the tube portion, and an opening provided at the other end, and a sealing member that seals the opening. The first holder covers the outer circumferential surface and the bottom of the cylindrical portion, Energy storage module.

3. The energy storage module according to claim 2, The bottom portion has the protrusion formed therein. Energy storage module.

4. The energy storage module according to claim 3, The side surface of the aforementioned protrusion is non-annular. Energy storage module.

5. The energy storage module according to claim 3, The inner surface of the bottom portion is recessed in the area corresponding to the protrusion. The aforementioned protrusion extends in the radial direction of the bottom portion. Energy storage module.

6. The energy storage module according to claim 3, Multiple protrusions are formed on the bottom portion. Energy storage module.

7. The energy storage module according to claim 6, The aforementioned protrusion is positioned at the bottom so as not to overlap with the central axis of the case. Energy storage module.

8. The energy storage module according to claim 2, The device further comprises a second holder that covers the sealing member and is located on the opposite side of the first holder in the extending direction of the energy storage device, At least a portion of the second holder facing the sealing member is thin-walled. Energy storage module.

9. The energy storage module according to claim 1, The gaps between the aforementioned energy storage devices are filled with a protective material, which then hardens. A groove is formed along the circumferential direction at the upper end of the aforementioned energy storage device. The protective material flows into the groove and hardens. Energy storage module.

10. The energy storage module according to claim 1, The gaps between the aforementioned energy storage devices are filled with a protective material, which then hardens. The protective material has a notch formed therein that exposes the side surface of the energy storage device. The aforementioned notch is formed in a position that does not interpose between adjacent energy storage devices. Energy storage module.

11. The energy storage module according to claim 1, The first holder has a notch formed therein that exposes the side surface of the energy storage device. The aforementioned notch is formed in a position that does not interpose between adjacent energy storage devices. Energy storage module.

12. The energy storage module according to claim 1, The first holder is obtained by impregnating a viscous material with a plurality of the energy storage devices and then hardening the material. Energy storage module.

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