Power storage module

Abstract

This power storage module (10) comprises: at least one cylindrical power storage device (20); a belt-like member (80) that is fixed to the outer peripheral surface of the power storage device (20) and surrounds the outer peripheral surface; and a lower holder (50) that has an accommodation part (51) that is a recess for accommodating the power storage device (20). A step part (53) into which the belt-like member (80) fits is formed in the accommodation part (51).

Description

Energy storage module

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

[0002] The power storage module is used as a power source equipped with a plurality of power storage devices. In the power storage module, the power storage devices are housed in a holder. In the power storage module disclosed in Patent Document 1, the power storage devices are fixed to the holder with an adhesive.

[0003] JP 2012-009389 A

[0004] In recent years, the environment in which power storage modules are used has become even more severe, and there is a demand for improving the reliability of power storage modules.

[0005] Therefore, an object of the present disclosure is to provide an energy storage module that can improve reliability.

[0006] The energy storage module according to the present disclosure comprises at least one cylindrical energy storage device, a strip-shaped member fixed to and surrounding the outer peripheral surface of the energy storage device, and a holder having a storage portion which is a recess for accommodating the energy storage device, and the storage portion is characterized in that a groove portion is formed in which the strip-shaped member fits.

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

[0008] Fig. 5 is an exploded perspective view showing an electricity storage module as an example of an embodiment; Fig. 6 is an axial cross-sectional view showing an electricity storage device; Fig. 7 is an axial cross-sectional view showing a fixing structure of an electricity storage device as an example of an embodiment; Fig. 8 is a cross-sectional view taken along line AA of Fig. 3; Fig. 9 is an axial cross-sectional view showing a fixing structure of an electricity storage device as another example of an embodiment; Fig. 10 is a cross-sectional view taken along line BB of Fig. 5; Fig. 11 is an axial cross-sectional view showing a fixing structure of an electricity storage device as another example of an embodiment.

[0009] 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.

[0010] [Electricity Storage Module] An electric power storage module 10 as an example of an embodiment will be described with reference to FIG.

[0011] 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.

[0012] In the following description of the energy storage module 10, the axial direction of a cylindrical energy storage device 20 (described later) may be referred to as the up-down direction. Also, the up-down direction may be referred to as the upper side or the lower side. Furthermore, the description may be referred to as the radial direction or the circumferential direction of the cylindrical energy storage device 20.

[0013] The energy storage module 10 comprises a plurality of energy storage devices 20, an upper holder 40 that holds the upper sides of the energy storage devices 20, a lower holder 50 that holds the lower sides of the energy storage devices 20, a first current collecting plate 60 arranged on the upper surface of the upper holder 40, a second current collecting plate 70 arranged on the bottom surface of the lower holder 50, and a strip-shaped member 80 (see Figures 3 and 4) that is arranged along the circumferential direction of the energy storage devices 20.

[0014] 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 substantially close 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 may be arranged such that the power storage devices closest to each other are located on all four sides.

[0015] [Power Storage Device] The power storage device 20 as an example of an embodiment will be described in detail with reference to FIG.

[0016] 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, 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 accommodates the electrode group 24 together with an electrolyte; 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 to the sealing body 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 body 26 and the inner circumferential surface of the opening of the outer can 25. Note that the positive electrode 21 may be electrically connected to the outer can 25, and the negative electrode 22 may be electrically connected to the outer can 25.

[0017] 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.

[0018] 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. Furthermore, 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 of the outer can 25 or between the electrode group 24 and the protrusion (groove 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. In the energy storage device 20, as described above, a terminal may be provided on the top surface of the sealing body 26, and a negative electrode terminal may be provided on the bottom surface of the outer can 25.

[0019] [Fixing Structure of the Power Storage Device] A fixing structure of the power storage device 20 in the power storage module 10, which is one example of an embodiment, will be described with reference to FIGS. 3 and 4. FIG.

[0020] In the energy storage module 10, the belt-shaped member 80 welded to the energy storage device 20 fits into a groove formed by the bottom surface of the upper holder 40 and the first step portion 53 of the lower holder 50, and the outer end portion 80A of the belt-shaped member 80 engages with the second step portion 54, which serves as an engaging portion, formed on the first step portion 53, thereby fixing the energy storage device 20 to the upper holder 40 and the lower holder 50. This reduces the need for adhesive and allows the energy storage device 20 to be fixed to the upper holder 40 and the lower holder 50. This improves the reliability of the energy storage module 10. However, the energy storage module of the present disclosure does not necessarily require the use of any adhesive when fixing the energy storage device. If necessary, adhesive may be interposed between the energy storage device and the holders.

[0021] As described above, the upper holder 40 holds the upper sides of the multiple power storage devices 20. The upper holder 40 is formed of, for example, a thermoplastic resin. Thermoplastic resins are broadly classified into general-purpose plastics and engineering plastics, and examples of such resins include polyethylene, polypropylene, polyamide, and ABS. The upper holder 40 has multiple storage sections 41, which are cylindrical depressions that accommodate the upper sides of the respective power storage devices 20, and openings 42 that open to the ceiling surfaces of the storage sections 41. From the perspective of securing the power storage devices 20, the inner diameter of the openings may be smaller than the outer diameter of the power storage devices 20. The top surfaces of the sealing bodies 26 of the power storage devices 20 accommodated in the storage sections 41 are exposed through the openings 42. A first current collector plate 60 is disposed on the upper surface of the upper holder 40.

[0022] The first current collector 60 is a conductive member that collects current from the positive electrodes 21 of the multiple power storage devices 20 in the power storage module 10. The first current collector 60 has a first lead 61 formed thereon that is connected to the top surface of the sealing body 26 that serves as the positive electrode terminal of the power storage device 20. The first lead 61 is formed in a rectangular shape, inclined downward from the top surface of the upper holder 40, and connected to the top surface of the sealing body 26 through the opening 42 of the upper holder 40.

[0023] As described above, the lower holder 50 holds the lower sides of the plurality of power storage devices 20. The lower holder 50 is formed of the same material as the upper holder 40, e.g., thermoplastic resin. The lower holder 50 has a plurality of storage sections 51, which are cylindrical recesses that accommodate the lower sides of the respective power storage devices 20, an opening 52 opened on the bottom surface of the storage section 51, a first step portion 53 that, together with the bottom surface of the upper holder 40, forms a groove into which a belt-shaped member 80 (described later) fits, and a second step portion 54 serving as an engaging portion with which an outer end portion 80A of the belt-shaped member 80 engages. The opening 52 exposes the bottom of the exterior can 25 of each power storage device 20 accommodated in the storage section 51. The first step portion 53 is formed in an annular shape along the circumferential direction of the storage section 51 at the edge of the storage section 51 on the upper surface of the lower holder 50. The second step portion 54 is formed as a step in the circumferential direction of the first step portion 53. A second current collector plate 70 is disposed on the bottom surface of the lower holder 50 .

[0024] In the present embodiment, the first step portion 53 and the second step portion 54 are formed on the lower holder 50, but the present disclosure is not limited to this. The first step portion and the second step portion may be formed on the upper holder. Also, the first step portion and the second step portion may be formed on the upper holder and the lower holder, and may be combined to form a groove portion and an engagement portion, respectively.

[0025] The upper holder 40 and the lower holder 50 are fixed to each other by a fixing means, such as a bolt that is inserted into a hole that passes through the upper holder 40 and the lower holder 50, and then the upper holder 40 and the lower holder 50 are fixed to each other by fastening the bolt and a nut.

[0026] The second current collector 70 is a conductive member that collects current from the negative electrodes 22 of the multiple power storage devices 20 in the power storage module 10. A second lead 71 is formed on the second current collector 70 and is connected to the bottom surface of the exterior can 25 that serves as the negative terminal of the power storage device 20. The second lead 71 is formed in an upwardly convex shape and is connected to the bottom surface of the exterior can 25 that is exposed from the opening 52 of the lower holder 50. However, the second current collector of the present disclosure is not limited to this, and may be disposed on the upper surface of the upper holder 40, for example, in the case where the shoulder of the exterior can 25 of the power storage device 20 serves as the negative terminal.

[0027] As described above, the belt-shaped member 80 is welded and fixed along the outer peripheral surface of the power storage device 20. The belt-shaped member 80 is provided directly below the boundary between the upper holder 40 and the lower holder 50 of the power storage device 20 in the axial direction. The belt-shaped member 80 is made of metal and formed in a belt shape. The belt-shaped member 80 is provided such that an end portion (outer end portion 80A) on one side and an end portion on the other side in the circumferential direction of the power storage device 20 overlap in a plan view (as viewed in the axial direction). The belt-shaped member 80 fits into a groove formed by the bottom surface of the upper holder 40 and the first step portion 53 of the lower holder 50.

[0028] In plan view (axial view), the outer end 80A of the belt-shaped member 80 protrudes outward in the radial direction of the power storage device 20 at the outer periphery by an amount corresponding to the thickness of the belt-shaped member 80. The outer end 80A engages with the second step portion 54 of the lower holder 50.

[0029] With the above configuration, the belt-shaped member 80 is fitted into a groove formed by the bottom surface of the upper holder 40 and the first step portion 53 of the lower holder 50, restricting axial movement of the belt-shaped member 80 in the upper holder 40 and the lower holder 50, and restricting axial movement of the electricity storage device 20 in the upper holder 40 and the lower holder 50. Furthermore, engagement of the outer end portion 80A with the second step portion 54 restricts circumferential movement of the belt-shaped member 80 in the lower holder 50, and restricts circumferential movement of the electricity storage device 20 in the lower holder 50. In this way, the electricity storage device 20 is fixed to the upper holder 40 and the lower holder 50.

[0030] Conventionally, when recycling energy storage modules, the energy storage device and holder were fixed together with an adhesive, making it impossible to separate the energy storage device (metal material) from the holder (resin material). In other words, the use of adhesive reduced the recycling efficiency of energy storage modules. Furthermore, in the manufacturing process of energy storage modules, the adhesive application process had large quality variations, making quality control time-consuming. Furthermore, a drying process was required to dry the adhesive. In other words, the use of adhesive could reduce the manufacturing efficiency of energy storage modules.

[0031] According to the energy storage module 10 of the present embodiment, the use of adhesive is reduced and the energy storage device 20 can be fixed to the upper holder 40 and the lower holder 50. This makes it possible to suppress the reduction in recycling efficiency and manufacturing efficiency that occurs when using the above-mentioned adhesive, and improves the recycling efficiency and manufacturing efficiency of the energy storage module 10.

[0032] 5 and 6, a fixing structure of the power storage device 20 of a power storage module 90, which is another example of an embodiment, will be described. Only the configuration that differs from the above-described power storage module 10 will be described below, and a description of the configuration that is the same as the power storage module 10 will be omitted.

[0033] In the energy storage module 90, a belt-shaped member 81 welded and fixed to the energy storage device 20 fits into a groove formed by the bottom surface of the upper holder 40 and the first step portion 53 of the lower holder 50, and the opening 81A of the belt-shaped member 81 fits into a protrusion 55 formed on the first step portion 53, thereby fixing the energy storage device 20 to the upper holder 40 and the lower holder 50.

[0034] The lower holder 50 has a storage section 51, an opening 52, a first step section 53 that, together with the bottom surface of the upper holder 40, forms a groove into which a belt-shaped member 81 (described later) fits, and a protrusion 55 that fits into the opening 81A of the belt-shaped member 81. The first step section 53 is formed in an annular shape along the circumferential direction of the storage section 51 at the edge of the storage section 51 on the upper surface of the lower holder 50. The protrusion 55 is formed to protrude radially inward from the first step section 53.

[0035] The belt-shaped member 81 is C-shaped in plan view (as viewed axially) and has an opening 81B between one end and the other end, into which the protrusion 55 of the lower holder 50 fits.

[0036] With the above configuration, the belt-shaped member 81 fits into a groove formed by the bottom surface of the upper holder 40 and the first step portion 53 of the lower holder 50, restricting axial movement of the belt-shaped member 81 in the upper holder 40 and the lower holder 50, and restricting axial movement of the electricity storage device 20 in the upper holder 40 and the lower holder 50. Furthermore, by fitting the protrusion 55 into the opening 81A, circumferential movement of the belt-shaped member 81 in the lower holder 50 is restricted, and circumferential movement of the electricity storage device 20 in the lower holder 50 is restricted. In this way, the electricity storage device 20 is fixed to the upper holder 40 and the lower holder 50.

[0037] According to the energy storage module 90 of the present embodiment, it is possible to fix the energy storage device 20 to the upper holder 40 and the lower holder 50. This makes it possible to suppress the reduction in recycling efficiency and manufacturing efficiency that occurs when using the above-mentioned adhesive, and it is possible to improve the recycling efficiency and manufacturing efficiency of the energy storage module 90.

[0038] A fixing structure of the energy storage device 20 of the energy storage module 100, which is another example of the embodiment, will be described with reference to Fig. 6. Only the configuration different from the above-described energy storage module 10 will be described below, and a description of the configuration similar to the energy storage module 10 will be omitted.

[0039] In the energy storage module 100, the belt-shaped member 80 welded to the energy storage device 20 fits into a groove formed by the bottom surface of the upper holder 40 and a first step portion 53 (not shown) of the lower holder 50, the outer end portion 80A of the belt-shaped member 80 engages with a second step portion 54 (not shown) serving as an engaging portion formed in the first step portion 53, and the leaf spring portion 82C serving as a biasing member of the belt-shaped member 82 biases the belt-shaped member 83 radially inward within the recess 56 formed in the first step portion 53, thereby fixing the energy storage device 20 to the lower holder 50. This allows the energy storage device 20 to be fixed to the upper holder 40 and the lower holder 50.

[0040] The lower holder 50 has an accommodation portion 51, an opening 52, a first step portion 53, a second step portion 54, and a recess 56 that accommodates the leaf spring portion 82C of the belt-shaped member 82. The recesses 56 are formed, for example, along the axial direction at opposing positions across the accommodation portion 51.

[0041] The belt-shaped member 82 is arranged so that one end and the other end overlap in a plan view (as viewed in the axial direction). The belt-shaped member 82 has leaf spring portions 82C as biasing members formed by bending portions of the belt-shaped member 82. The leaf spring portions 82C are formed, for example, at positions facing each other across the belt-shaped member 82. The leaf spring portions 82C are accommodated in the recesses 56 of the lower holder 50. The leaf spring portions 82C are formed by bending the rear side in the insertion direction into the lower holder 50. This makes it easier to insert the leaf spring portions 82C into the lower holder 50. The leaf spring portions 82C may be formed, for example, by forming a notch in a portion of the belt-shaped member 82 and bending the tongue-shaped region surrounded by the notch so that it protrudes outward in the radial direction. The area between the tip and base of this tongue-shaped leaf spring portion 82C may be further bent radially so that the tip portion falls toward the storage device, forming a bent portion of the leaf spring portion 82C that protrudes radially outward, and this bent portion may be abutted against the recess 56.

[0042] With the above configuration, the belt-shaped member 80 fits into a groove formed by the bottom surface of the upper holder 40 and the first step portion 53 of the lower holder 50, thereby restricting axial movement of the belt-shaped member 80 in the upper holder 40 and the lower holder 50, and thus restricting axial movement of the electricity storage device 20 in the upper holder 40 and the lower holder 50. Furthermore, the outer end portion 80A engages with the second step portion 54, thereby restricting circumferential movement of the belt-shaped member 80 in the lower holder 50, and thus restricting circumferential movement of the electricity storage device 20 in the lower holder 50. Furthermore, the leaf spring portion 82C biases the belt-shaped member 82 radially inward, thereby improving the fixing force of the electricity storage device 20 in the accommodation portion 51. As a result, the electricity storage device 20 is more firmly fixed to the upper holder 40 and the lower holder 50.

[0043] [Summary] The present disclosure is further described by the following embodiments. Configuration 1: An energy storage module comprising: at least one cylindrical energy storage device; a strip-shaped member fixed to and surrounding an outer peripheral surface of the energy storage device; and a holder having a housing portion that is a recess that houses the energy storage device, wherein a groove portion into which the belt-shaped member fits is formed in the housing portion. Configuration 2: The energy storage module according to configuration 1, wherein a dimension of the belt-shaped member in the circumferential direction of the energy storage device is longer than the dimension of the energy storage device in the circumferential direction, both ends of the belt-shaped member in the circumferential direction overlap, and an engaging portion is formed in the groove portion that engages with outer peripheral ends of both ends of the belt-shaped member. Configuration 3: The energy storage module according to configuration 1 or 2, wherein a dimension of the belt-shaped member in the circumferential direction of the energy storage device is shorter than the dimension of the energy storage device in the circumferential direction, both ends of the belt-shaped member in the circumferential direction are spaced apart in the circumferential direction, and a convex portion that fits between the both ends of the belt-shaped member is formed on an inner surface of the groove. Configuration 4: The energy storage module according to any one of configurations 1 to 3, wherein the belt-shaped member is provided with a biasing member that biases the belt-shaped member radially inward. Configuration 5: The energy storage module according to configuration 4, wherein the biasing member is formed to protrude from the belt-shaped member outward from the energy storage device in the radial direction, and the biasing member abuts against an inner surface of a recess formed in the groove. Configuration 6: The energy storage module according to any one of configurations 1 to 5, wherein the belt-shaped member is fixed to the energy storage device by welding.

[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, 90, 100 Energy storage module, 20 Energy storage device, 21 Positive electrode, 22 Negative electrode, 23 Separator, 24 Electrode group, 25 Outer can, 25A Groove portion, 26 Sealing body, 27 Positive electrode tab, 28 Negative electrode tab, 29 Gasket, 30 Insulating plate, 40 Upper holder, 41 Storage portion, 42 Opening, 50 Lower holder, 51 Storage portion, 52 Opening, 53 First step portion (groove portion), 54 Second step portion (engagement portion), 55 Convex portion, 56 Storage portion, 60 First current collector, 61 First lead, 70 Second current collector, 71 Second lead, 80, 81, 82 Strip-shaped member, 80A Outer peripheral end portion, 81B Opening, 82C Leaf spring portion (biasing member)

Claims

1. An energy storage module comprising: at least one cylindrical energy storage device; a belt-shaped member fixed to and surrounding an outer peripheral surface of the energy storage device; and a holder having a storage portion that is a recess for storing the energy storage device, wherein a groove portion is formed in which the belt-shaped member fits.

2. An energy storage module as described in claim 1, wherein the circumferential dimension of the belt-shaped member in the circumferential direction of the energy storage device is longer than the circumferential dimension of the energy storage device, both ends of the belt-shaped member in the circumferential direction overlap, and an engagement portion is formed in the groove portion with which the outer peripheral ends of both ends of the belt-shaped member engage.

3. An energy storage module as described in claim 1, wherein the circumferential dimension of the belt-shaped member in the energy storage device is shorter than the circumferential dimension of the energy storage device, both ends of the belt-shaped member in the circumferential direction are spaced apart in the circumferential direction, and a convex portion is formed on the inner surface of the groove portion to fit between the both ends of the belt-shaped member.

4. An energy storage module according to claim 1, wherein the belt-shaped member is provided with a biasing member that biases the belt-shaped member radially inward.

5. An energy storage module according to claim 4, wherein the biasing member is formed so as to protrude outward from the energy storage device in the radial direction from the band-shaped member, and the biasing member abuts against an inner surface of a recess formed in the groove.

6. The energy storage module according to any one of claims 1 to 5, wherein the belt-shaped member is fixed to the energy storage device by welding.

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