Power storage module

Abstract

This power storage module (10) comprises: a cylindrical power storage device (20); a retaining ring (80) provided along the side circumferential surface of the power storage device; and a holder that has an accommodation part (51) that is a recess, and that accommodates the power storage device (80) in the accommodation part (51). The retaining ring (80) has a first protruding section (80A) that protrudes in the radial direction. The accommodation part (51) has, on the inner surface thereof, a groove section (43) into which the retaining ring (80) is fitted. The groove section (43) of the accommodation part (51) has, on the inner surface thereof, a recessed section (54) into which the first protruding section (80) is fitted.

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 environments in which power storage modules are used have become increasingly harsh, and there is a demand for improved reliability of power storage modules.

[0005] The energy storage module according to the present disclosure comprises a cylindrical energy storage device, a retaining ring provided along the side peripheral surface of the energy storage device, and a holder having a recessed accommodation portion that accommodates the energy storage device in the accommodation portion, wherein the retaining ring has a first convex portion that protrudes radially, the accommodation portion has an inner surface having a groove portion into which the retaining ring fits, and the groove portion of the accommodation portion has an inner surface having a recess into which the first convex portion fits.

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

[0007] Fig. 3 is an exploded perspective view showing an electricity storage module as an example of an embodiment; Fig. 4 is an axial cross-sectional view showing an electricity storage device; Fig. 5 is an axial cross-sectional view showing a fixing structure of an electricity storage device as an example of an embodiment; Fig. 6 is a cross-sectional view taken along line AA of Fig. 3; Fig. 7 is an axial cross-sectional view showing a fixing structure of an electricity storage device as another example of an embodiment; Fig. 8 is an axial cross-sectional view showing a fixing structure of an electricity storage device as another example of an 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] [Electricity Storage Module] An electric power storage module 10 as an example of an embodiment will be described with reference to FIG.

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

[0011] 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.

[0012] 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 retaining ring 80 (see Figures 3 and 4) that is arranged along the circumferential direction of the energy storage devices 20.

[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 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.

[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, 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 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. The outer can 25 may have a rectangular tubular shape rather than a cylindrical shape.

[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. 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, the positive electrode terminal may be configured on the top surface of the sealing body 26, and the negative electrode terminal may be configured on the bottom surface of the outer can 25.

[0018] [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.

[0019] In the energy storage module 10, the retaining ring 80 press-fitted into the energy storage device 20 fits into a groove formed by the bottom surface of the upper holder 40 and the step portion 53 of the lower holder 50, and the convex portion 80A of the retaining ring 80 fits into the recessed portion 54 formed in the 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 makes it possible to fix the energy storage device 20 to the upper holder 40 and the lower holder 50. This improves the reliability of the energy storage module. However, it is not essential that the energy storage module of the present disclosure does not use any adhesive when fixing the energy storage device. If necessary, adhesive may be interposed between the energy storage device and the holder.

[0020] 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.

[0021] 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.

[0022] 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, for example, a 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 sections 51, a step portion 53 that forms a groove with the bottom surface of the upper holder 40 and into which a snap ring 80 (described later) fits, and a recess 54 into which a protrusion 80A of the snap ring 80 (described later) fits. The bottom of the outer can 25 of the power storage device 20 accommodated in the storage section 51 is exposed from the opening 52. The 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 recess 54 is formed to be recessed radially outward from the step portion 53. A second current collector plate 70 is disposed on the bottom surface of the lower holder 50 .

[0023] In this embodiment, the step portion 53 and the recessed portion 54 are formed in the lower holder 50, but the present invention is not limited to this. The step portion and the recessed portion may be formed in the upper holder. Also, the step portion and the recessed portion may be formed in the upper holder and the lower holder, and the groove portion and the recessed portion may be formed by joining them.

[0024] 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.

[0025] 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.

[0026] As described above, the retaining ring 80 is provided along the circumferential direction of the power storage device 20. The retaining ring 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 retaining ring 80 is made of metal, and its surface is subjected to an insulating treatment. The retaining ring 80 may also be made of insulating resin. The retaining ring 80 is formed in a C-shape in plan view (as viewed from the axial direction). The retaining ring 80 fits into a groove formed by the bottom surface of the upper holder 40 and the step portion 53 of the lower holder 50. The retaining ring 80 is press-fitted into the power storage device 20 and fixed.

[0027] The retaining ring 80 is provided with a protrusion 80A that protrudes radially outward. The protrusion 80A is formed at both ends of the C-shape of the retaining ring 80. The protrusion 80A is formed to protrude radially outward. However, the protrusion of the present invention is not limited to this and may be formed at any position in the circumferential direction of the retaining ring 80. The protrusion 80A fits into the recess 54 of the lower holder 50.

[0028] In the manufacturing process of the energy storage module 10, for example, a retaining ring 80 is pressed into the energy storage device 20, the energy storage device 20 is accommodated in the accommodation portion 41 of the upper holder 40, the energy storage device 20 is accommodated in the accommodation portion 51 of the lower holder 50 (the lower holder 50 is assembled to the upper holder 40), and the upper holder 40 and the lower holder 50 are fixed by a fixing means.

[0029] With the above configuration, the retaining ring 80 fits into a groove formed by the bottom surface of the upper holder 40 and the step portion 53 of the lower holder 50, restricting axial movement of the retaining ring 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, by fitting the convex portion 80A into the concave portion 54, circumferential movement of the retaining ring 80 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.

[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, it is possible to reduce the use of adhesives and to fix the energy storage device 20 to the upper holder 40 and the lower holder 50. This makes it possible to prevent a decrease in recycling efficiency and a decrease in manufacturing efficiency that would occur due to the use of the adhesives described above, and it is possible to improve the recycling efficiency and manufacturing efficiency of the energy storage module 10.

[0032] [Fixing Structure of Energy Storage Device According to Another Embodiment] A fixing structure of the energy storage device 20 of an energy storage module 90, which is another example of an embodiment, will be described using Fig. 5. Only configurations that differ from the above-described energy storage module 10 will be described below, and a description of configurations that are the same as those of the energy storage module 10 will be omitted.

[0033] In the electricity storage module 90, the retaining ring 81 press-fitted into the groove 25A of the electricity storage device 20 fits into the groove formed by the bottom surface of the upper holder 40 and the step 53 of the lower holder 50, and the convex portion 81A of the retaining ring 81 fits into the concave portion 54 formed in the step 53, thereby fixing the electricity storage device 20 to the upper holder 40 and the lower holder 50. This makes it possible to fix the electricity storage device 20 to the upper holder 40 and the lower holder 50 without using adhesive.

[0034] In this embodiment, the axial lengths (heights) of the upper holder 40 and the lower holder 50 are determined so that the boundary between the upper holder 40 and the lower holder 50 is located at the upper end of the groove portion 25A of the power storage device 20. In this embodiment, the axial length of the lower holder 50 is sufficiently greater than the axial length of the upper holder 40.

[0035] In the manufacturing process of the energy storage module 90, for example, a retaining ring 81 is pressed into the groove portion 25A of the energy storage device 20, the energy storage device 20 is accommodated in the accommodation portion 41 of the upper holder 40, the energy storage device 20 is accommodated in the accommodation portion 51 of the lower holder 50 (the lower holder 50 is assembled to the upper holder 40), and the upper holder 40 and the lower holder 50 are fixed by a fixing means.

[0036] With the above configuration, the retaining ring 81 fits into a groove formed by the bottom surface of the upper holder 40 and the step portion 53 of the lower holder 50, restricting axial movement of the retaining ring 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, the convex portion 81A fits into the concave portion 54, restricting circumferential movement of the retaining ring 81 in the lower holder 50, and restricting 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.

[0037] 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.

[0038] In the energy storage module 100, a retaining ring 82 press-fitted into groove 25A of the energy storage device 20 fits into a groove formed by step 43 of the upper holder 40 and the upper surface of the lower holder 50, and a convex portion 82A of the retaining ring 82 fits into a concave portion 44 formed in step 43, thereby fixing the energy storage device 20 to the upper holder 40. Further, a retaining ring 83 press-fitted into the energy storage device 20 engages with a step 53 formed in the lower holder 50, and a convex portion 83A of the retaining ring 83 fits into a concave portion 54 formed in step 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.

[0039] The upper holder 40 has a storage portion 41, an opening 42, a step portion 43 that forms a groove with which the retaining ring 82 engages, and a recessed portion 44 into which the protruding portion 82A of the retaining ring 83 fits. The step portion 43 is formed in an annular shape along the circumferential direction of the storage portion 41 at the edge of the storage portion 41 on the bottom surface of the upper holder 40. The recessed portion 44 is formed to be recessed radially outward from the step portion 43.

[0040] The lower holder 50 has a storage portion 51, an opening 52, a step portion 53 that forms a groove with which the retaining ring 83 engages, and a recessed portion 54 into which the protruding portion 83A of the retaining ring 83 fits. The step portion 53 is formed in an annular shape along the circumferential direction of the storage portion 51 at a midpoint of the storage portion 51. The recessed portion 54 is formed to be recessed radially outward from the step portion 53. The recessed portion 54 is formed along the axial direction up to the upper surface of the lower holder 50. The recessed portion 54 is provided at a different position in the circumferential direction from the recessed portion 44 of the upper holder 40 described above.

[0041] The retaining ring 82 is similar to the retaining ring 81 of the above-described storage module 90, and therefore a description thereof will be omitted.

[0042] The retaining ring 83 is provided below the groove portion 25A of the power storage device 20. The retaining ring 83 engages with the step portion 53 of the lower holder 50. The retaining ring 83 is press-fitted and fixed into the power storage device 20. The retaining ring 83 is provided with a convex portion 83A that protrudes radially outward. The convex portion 83A fits into the concave portion 54 of the lower holder 50. The convex portion 83A is provided at a different position in the circumferential direction from the convex portion 82A of the retaining ring 82 described above.

[0043] In the manufacturing process of the energy storage module 90, for example, a retaining ring 82 is pressed into the groove portion 25A of the energy storage device 20, a retaining ring 83 is pressed into the energy storage device 20, the energy storage device 20 is accommodated in the accommodation portion 41 of the upper holder 40, the energy storage device 20 is accommodated in the accommodation portion 51 of the lower holder 50 (the lower holder 50 is assembled to the upper holder 40), and the upper holder 40 and the lower holder 50 are fixed by a fixing means.

[0044] With the above configuration, the retaining ring 82 engages with the step portion 43 of the upper holder 40, restricting the axial movement of the retaining ring 82 in the upper holder 40, and the retaining ring 83 engages with the step portion 53 of the lower holder 50, restricting the axial movement of the retaining ring 83 in the lower holder 50, thereby restricting the axial movement of the storage device 20 in the upper holder 40 and the lower holder 50.

[0045] Furthermore, the engagement of the convex portion 82A with the concave portion 44 restricts the circumferential movement of the retaining ring 83 in the upper holder 40, and the engagement of the convex portion 83A with the concave portion 54 restricts the circumferential movement of the retaining ring 83 in the lower holder 50, thereby restricting the circumferential movement of the electricity storage device 20 in the upper holder 40 and the lower holder 50. In this way, the electricity storage device 20 is fixed to the upper holder 40 and the lower holder 50.

[0046] Summary The present disclosure is further described by the following embodiments.

[0047] Configuration 1: An energy storage module comprising: a cylindrical energy storage device; a retaining ring provided along a side peripheral surface of the energy storage device; and a holder having a recessed accommodation portion, the holder accommodating the energy storage device in the accommodation portion, wherein the retaining ring has a first protrusion protruding radially, the accommodation portion has an inner surface having a groove portion into which the retaining ring fits, and the groove portion of the accommodation portion has an inner surface having a recess portion into which the first protrusion fits.

[0048] Configuration 2: The energy storage module according to configuration 1, comprising a plurality of energy storage devices, each of the plurality of energy storage devices being the energy storage device, and the plurality of energy storage devices being housed in the holder.

[0049] Configuration 3: The energy storage module according to configuration 1 or 2, wherein the retaining ring is press-fitted into the energy storage device and fixed thereto.

[0050] Configuration 4: The energy storage module according to any one of configurations 1 to 3, wherein the groove of the housing portion extends along a circumferential direction of the energy storage device, and the retaining ring is disposed in the groove.

[0051] Configuration 5: The energy storage module according to any one of configurations 1 to 4, further comprising a plurality of retaining rings, each of which is the retaining ring, each of which is provided along the side circumferential surface of the energy storage device, and each of which is arranged such that the first protrusions are at different positions in the circumferential direction.

[0052] Configuration 6: The energy storage module according to any one of configurations 1 to 5, wherein the retaining ring is C-shaped, and the retaining ring further has a second convex portion, the first convex portion is provided at one end of the C-shaped retaining ring, and the second convex portion is provided at the other end of the C-shaped retaining ring.

[0053] 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.

[0054] 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 26 Sealing body 27 Positive electrode tab 28 Negative electrode tab 29 Gasket 30 Insulating plate 40 Upper holder 41 Storage section 42 Opening 43 Stepped portion (groove) 44 Recessed portion 50 Lower holder 51 Storage section 52 Opening 53 Stepped portion (groove) 54 Recessed portion 60 First current collector plate 61 First lead 70 Second current collector plate 71 Second lead 80, 81, 82, 83 Retaining ring 80A, 81A, 82A, 83A Convex portion

Claims

1. An energy storage module comprising: a cylindrical energy storage device; a retaining ring provided along a side peripheral surface of the energy storage device; and a holder having a storage portion which is a recess, the storage device being stored in the storage portion, wherein the retaining ring has a first convex portion protruding in the radial direction, the storage portion has an inner surface having a groove portion into which the retaining ring fits, and the groove portion of the storage portion has an inner surface having a recess into which the first convex portion fits.

2. An energy storage module according to claim 1, comprising a plurality of energy storage devices, each of the plurality of energy storage devices being the energy storage device, and the plurality of energy storage devices being housed in the holder.

3. The energy storage module according to claim 1, wherein the retaining ring is press-fitted into the energy storage device and fixed thereto.

4. An energy storage module according to claim 3, wherein the groove of the accommodating part extends in a circumferential direction of the energy storage device, and the retaining ring is disposed in the groove.

5. An energy storage module as described in claim 4, comprising a plurality of retaining rings, each of the plurality of retaining rings being the retaining ring, each of the plurality of retaining rings being provided along the side peripheral surface of the energy storage device, and the plurality of retaining rings being arranged such that the first protrusions of each of the retaining rings are at different positions in the circumferential direction.

6. An energy storage module according to any one of claims 1 to 5, wherein the retaining ring is C-shaped, and the retaining ring further has a second convex portion, the first convex portion being provided at one end of the C-shaped retaining ring, and the second convex portion being provided at the other end of the C-shaped retaining ring.

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