Electric power storage module

Abstract

A power storage module (10) comprises: a plurality of power storage devices (20); a holder (40) that holds the plurality of power storage devices (20); and a housing (50) that accommodates the holder (40). The housing (50) includes a lower housing (51) and an upper housing (52) arranged in the vertical direction. The lower housing (51) and the upper housing (52) are sealed by a sealing structure (60). The sealing structure (60) includes a first groove (61) that is provided on a first contact surface (51C) of the lower housing (51) with the upper housing (52), a ridge-shaped projection (62) that is provided on a second contact surface (52C) of the upper housing (52) with the lower housing (51) and housed in the first groove (61), and a liquid gasket (65) provided between the first groove (61) and the projection (62). The center of the first groove (61) and the center of the projection (62) are offset in the width direction.

Description

Power storage module

[0001] The present disclosure relates to a power storage module.

[0002] A power storage module including a plurality of power storage devices, a holder that holds the plurality of power storage devices, and a housing that houses the holder is known (for example, Patent Document 1). The power storage module may be used outdoors. For the housing of a power storage module used outdoors, a sealing structure for waterproofing and dustproofing is required.

[0003] In the sealing structure of the housing, a liquid gasket may be used. In order to improve the sealing performance in the sealing structure using a liquid gasket, it is important to suppress the movement of the liquid gasket and ensure the contact area between the liquid gasket and the housing.

[0004] Japanese Patent Application Laid-Open No. 2017-152165

[0005] Here, there is a demand for a power storage module that can be used under a wider range of conditions and has better performance.

[0006] Therefore, an object of the present disclosure is to provide a power storage module capable of improving performance.

[0007] The power storage module according to the present disclosure is a power storage module including a plurality of power storage devices, a holder that holds the plurality of power storage devices, and a housing that houses the holder, wherein the housing includes a first housing and a second housing arranged in a first direction, the first housing and the second housing are sealed by a sealing structure, the sealing structure includes a first groove provided on a first contact surface of the first housing with the second housing, a ridge-shaped protrusion provided on a second contact surface of the second housing with the first housing and housed in the first groove, and a liquid gasket provided between the first groove and the protrusion, and the center of the first groove and the center of the protrusion are offset in a second direction orthogonal to the first direction.

[0008] According to the power storage module of the present disclosure, the performance can be improved.

[0009] This is a schematic cross-sectional view showing an energy storage module, which is an example of an embodiment. This is a cross-sectional view showing an energy storage device according to an embodiment. This is a detailed view of part A in Figure 1, showing a sealing structure, which is an example of an embodiment. This is a detailed view of part A in Figure 1, showing another example of a sealing structure, which is another example of an embodiment.

[0010] An example of an embodiment of this disclosure is described in detail below. In the following description, specific shapes, materials, directions, numerical values, etc., are examples provided to facilitate understanding of this disclosure and can be modified as appropriate to suit the application, purpose, specifications, etc.

[0011] [Energy Storage Module] An example of an embodiment, the energy storage module 10, will be described using Figure 1.

[0012] The energy storage module 10 is mounted on an electric vehicle as a power source for the motor that drives the electric vehicle. However, the energy storage module of this disclosure is not limited to being mounted on an electric vehicle, and may be used as a power source for electric equipment driven by motors, such as power tools, electric assist bicycles, electric motorcycles, electric wheelchairs, electric tricycles, and electric carts. Furthermore, the applications of the energy storage module of this disclosure are not limited, and may be used as a power source for various electrical equipment used indoors and outdoors, such as cleaners, wireless devices, lighting devices, digital cameras, and video cameras.

[0013] As will be described in detail later, the energy storage module 10 makes it possible to improve energy density while maintaining the sealing performance of the sealing structure 60 of the housing 50. In the following, the axial direction of the energy storage device 20 housed in the energy storage module 10 may be considered as the vertical direction, and each component may be described using the upper or lower side.

[0014] Each energy storage module 10 comprises a plurality of energy storage devices 20, a holder 40 for holding the plurality of energy storage devices 20, and a housing 50 for housing the holder 40, the details of which will be described later.

[0015] Multiple energy storage devices 20 may be packed as densely as possible within the energy storage module 10, with safety in mind, and adjacent energy storage devices 20 may be arranged in close proximity to each other. For example, in a plan view, six energy storage devices 20 may surround one energy storage device 20 (or be arranged in a staggered pattern). Alternatively, multiple energy storage devices 20 may be arranged such that the closest energy storage devices 20 are placed on each of the four sides. Details of the energy storage devices 20 will be described later.

[0016] The holder 40 holds the energy storage device 20. The holder 40 is divided vertically into a lower holder 41 and an upper holder 42. If the holder 40 has electrical insulation properties, it is made of, for example, a thermoplastic resin. Thermoplastic resins are broadly classified into general-purpose plastics and engineering plastics, and polycarbonate, polybutylene terephthalate, etc. are used. The lower holder 41 and the upper holder 42 are fixed to each other via a fixing member or using locking parts provided on each holder.

[0017] The lower holder 41 has a plurality of housing sections 43, which are cylindrical recesses that accommodate the lower portion of each energy storage device 20. Positive electrode current collector plates and negative electrode current collector plates for collecting current from the energy storage device 20 may be provided on the lower surface of the lower holder 41. Each of the plurality of housing sections 43 has a through hole that forms an opening on the lower surface of the lower holder 41, and a plurality of leads of the positive electrode current collector plate and negative electrode current collector plate may be inserted through this opening and connected to the sealing body 26 or the outer casing 25.

[0018] The upper holder 42 has a plurality of accommodating sections 44, which are cylindrical recesses that house the upper portion of each energy storage device 20. Positive electrode current collector plates and negative electrode current collector plates for collecting current from the energy storage device 20 may be provided on the upper surface of the upper holder 42. Each of the plurality of accommodating sections 44 has a through hole that forms an opening on the upper surface of the upper holder 42, and a plurality of leads of the positive electrode current collector plate and negative electrode current collector plate are inserted through this opening, and these leads may be connected to the sealing body 26 or the outer casing 25.

[0019] The housing 50 houses the holder 40. The housing 50 is divided in the vertical direction (first direction) into a lower housing 51 (first housing) and an upper housing 52 (second housing). In this disclosure, the housing may also be divided in the left-right direction or the front-back direction. The housing 50 is made of a metal such as aluminum. However, the housing 50 is not limited to metal and may be made of resin.

[0020] The lower housing 51 has a plate-shaped first base portion 51A, an annular first wall portion 51B extending vertically from the first base portion 51A, and a housing portion 53 in which the lower part of the holder 40 is housed. The upper housing 52 has a plate-shaped second base portion 52A, an annular second wall portion 52B extending vertically from the second base portion 52A, and a housing portion 54 in which the upper part of the holder 40 is housed. In the housing 50, the lower housing 51 and the upper housing 52 are fixed together by a fixing structure (not shown). The fixing structure may be, for example, a fixing structure using fastening members such as screws and bolts, or a structure in which an engaging portion and a claw portion are engaged. In addition, in the housing 50, the lower housing 51 and the upper housing 52 are sealed together by a sealing structure 60, which will be described in detail later.

[0021] [Energy Storage Device] The energy storage device 20 according to the embodiment will be described with reference to Figure 2.

[0022] In this embodiment, the energy storage device 20 is a cylindrical lithium-ion secondary battery, but it may also be a nickel-metal hydride battery, a capacitor, or the like. The energy storage device 20 includes, for example, an electrode group 24 in which a strip-shaped positive electrode 21 and a strip-shaped negative electrode 22 are wound with a strip-shaped separator 23 in between, a cylindrical outer container 25 that houses the electrode group 24 together with an electrolyte, a sealing body 26 that seals the opening of the outer container 25 in an insulated state, a foil-shaped positive electrode lead 27 that electrically connects the positive electrode 21 and the sealing body 26, and a negative electrode lead 28 that electrically connects the negative electrode 22 and the outer container 25. An insulating gasket 29 may be placed between the outer circumference of the sealing body 26 and the inner surface of the opening of the outer container 25.

[0023] An annular groove 25A is formed on the outer circumferential surface of the outer can 25 on the opening side. This groove 25A is formed as an annular projection on the inner circumferential surface of the outer can 25. The gasket 29 and the sealing body 26 are placed on this annular projection inside the outer can 25. Furthermore, the opening end of the outer can 25 is crimped so that it bends inward with the gasket 29 positioned on the inner circumferential side. The opening of the outer can 25 is sealed by the sealing body 26 being sandwiched axially between the crimped opening end and the projection via the gasket 29.

[0024] The sealing body 26 may be provided with a current interruption mechanism (CID) or an exhaust valve that ruptures when the pressure inside the outer casing 25 exceeds a predetermined level. An insulating plate 30 may also be provided between the electrode group 24 and the bottom of the outer casing 25, or between the electrode group 24 and the protrusion (groove 25A) to insulate the electrode group 24 from the outer casing 25. If an insulating plate 30 is provided, the positive electrode lead 27 may extend through a through hole formed in the insulating plate 30. The negative electrode lead 28 may extend either through a through hole formed in the insulating plate 30 or by bypassing the insulating plate 30. In the energy storage device 20, as described above, the positive electrode terminal may be located on the top surface of the sealing body 26, and the negative electrode terminal may be located on the crimped shoulder portion of the outer casing 25.

[0025] However, the energy storage device of this disclosure is not limited to the above configuration. In the energy storage device of this disclosure, an outer casing and a sealing plate that crimps and closes the opening of the outer casing may be electrically connected, and a terminal member connected to the positive electrode as a first terminal may be placed in an insertion hole formed in the bottom of the outer casing, insulated from the outer casing. In this case, the sealing plate connected to the negative electrode and the outer casing function as a second terminal.

[0026] [Sealing Structure] An example of a sealing structure 60, which is an embodiment, will be described using Figure 3.

[0027] In the following, the direction along the first groove 61 or projection 62 may be described as the depth direction. Also, the vertical direction (first direction) and the direction perpendicular to the depth direction may be described as the width direction (second direction).

[0028] As described above, the sealing structure 60 seals the lower housing 51 and the upper housing 52, thereby sealing the housing 50. The sealing structure 60, as will be described in detail later, improves the sealing performance of the housing 50.

[0029] By improving the sealing performance of the sealing structure 60, sufficient sealing performance can be maintained even when the widthwise size of the sealing structure 60 is reduced. In other words, even when the volume of the first base 51A, first wall 51B, second base 52A, and second wall 52B surrounding the housing space of the housing 50 (lower housing 51 and upper housing 52) is reduced, the sealing performance of the sealing structure 60 of the housing 50 can be maintained.

[0030] This makes it possible to improve the energy density of the energy storage module 10 while maintaining the sealing performance of the sealing structure 60 of the housing 50. As a result, the performance of the energy storage module 10 can be improved.

[0031] The sealing structure 60 includes a first groove 61 provided on the first contact surface 51C of the lower housing 51 with the upper housing 52 and extending in the depth direction, a ridge-shaped projection 62 provided on the second contact surface 52C of the upper housing 52 with the lower housing 51 and housed in the first groove 61 and extending in the depth direction, and a liquid gasket 65 provided between the first groove 61 and the projection 62.

[0032] The first groove 61 is formed to be recessed downward on the first contact surface 51C of the lower housing 51 and the upper housing 52. In the width direction, the first groove 61 is provided so as to be sandwiched between a pair of first regions 51D on the first contact surface 51C. The first groove 61 is formed along the edge of the housing portion 53 of the lower housing 51. The first groove 61 is formed in a rectangular shape in a cross-sectional view along the vertical direction. The projection 62 is housed in the first groove 61. A gap G is formed between the first groove 61 and the projection 62.

[0033] Furthermore, a liquid gasket 65 is provided inside the first groove 61. Preferably, the liquid gasket 65 is provided in close contact with the bottom surface 61A of the first groove 61 (or the wall portion 61B of the first groove 61 that extends in the vertical direction).

[0034] The first groove 61 helps to suppress the movement of the liquid gasket 65. Furthermore, the first groove 61 increases the contact area between the lower housing 51 and the liquid gasket 65. This improves the sealing performance of the sealing structure 60.

[0035] The projection 62 is housed in the first groove 61. The projection 62 is housed in the first groove 61 such that there is a gap G between the first groove 61 and the projection 62 in the vertical and width directions. The center of the first groove 61 is offset from the center of the projection 62 in the width direction. More specifically, the center of the first groove 61 is offset outward in the width direction from the center of the projection 62.

[0036] Here, the center of the projection 62 is the center of the end face on the first groove side (tip) of the projection 62 in the first direction. The center of the first groove 61 is the center of the bottom surface furthest from the projection 62 in the first direction.

[0037] The projection 62 is formed to protrude downward on the second contact surface 52C of the upper housing 52 and the lower housing 51. In the width direction, the projection 62 is provided so as to be sandwiched between a pair of second regions 52D on the second contact surface 52C. The projection 62 is formed along the edge of the housing portion 54 of the upper housing 52. The projection 62 is formed in a rectangular shape in a cross-sectional view along the vertical direction (a cross-sectional view perpendicular to the depth direction). The projection 62 is housed in the first groove 61. A gap G is formed between the projection 62 and the first groove 61. As described above, the center of the projection 62 is offset from the center of the first groove 61 in the width direction. Also, the center of the projection 62 is offset inward in the width direction compared to the center of the first groove 61.

[0038] The liquid gasket 65, for example, is fluid at room temperature, and after being applied to the joint surface, it dries or becomes uniform after a certain period of time, forming an elastic or adhesive thin layer. The material of the liquid gasket 65 is preferably an epoxy adhesive with methanol resistance, an epoxy-modified silicone adhesive, a silicone adhesive, a fluorine-based adhesive, or an elastic adhesive such as butyl rubber-based urethane RTV rubber or silicone RTV rubber.

[0039] The gap G is formed between the first groove 61 and the protrusion 62 in the vertical and width directions, with the first groove 61 being housed in the protrusion 62. The gap G is enclosed by the contact between a pair of first regions 51D and a pair of second regions 52D. In the energy storage module of this disclosure, the pair of first regions and the pair of second regions do not necessarily have to be in contact.

[0040] The gap G includes a first gap G1 located on the outside and a second gap G2 located on the inside in the width direction. As described above, since the center of the first groove 61 and the center of the projection 62 are offset in the width direction, the width of the first gap G1 is greater than the width of the second gap G2. However, the width of the first gap G1 is sufficiently smaller than the width of the second gap G2.

[0041] For example, in a configuration where the center of the first groove 61 and the center of the protrusion 62 are in the same position in the width direction, and the width of the first gap G1 and the width of the second gap G2 are the same, when assembling the energy storage module 10, when the protrusion 62 is fitted into the first groove 61 where the liquid gasket 65 is provided in order to seal the lower housing 51 and the upper housing 52 (hereinafter referred to as sealing), the liquid gasket 65 may rise up into the first gap G1, or the liquid gasket 65 may rise up into the second gap G2. In other words, variations in the rise of the liquid gasket 65 occur. In this case, the sealing performance of the sealing structure 60 may be reduced.

[0042] According to the sealing structure 60 of this embodiment, since the width of the first gap G1 is greater than the width of the second gap G2 in the width direction, the liquid gasket 65 rises towards the first gap G1, which offers less resistance, during sealing. This suppresses variations in the rise of the liquid gasket 65 in the gap G. As a result, the sealing performance of the sealing structure 60 can be improved.

[0043] Also, by forming the width of the first gap G1 to be sufficiently smaller than the width of the second gap G2, the sealing performance of the housing 50 can be improved. For example, even when the power storage module 10 is submerged and the liquid gasket 65 is pressed inward in the width direction by water pressure, since the first gap G1 is sufficiently small, the liquid gasket 65 cannot enter the first gap G1, and the housing 50 can be sealed.

[0044] [Other Embodiments] A sealing structure 70, which is another example of the embodiment, will be described with reference to FIG. 4. Hereinafter, only the configuration different from the above-described sealing structure 60 will be described. Also, for the same members as those in the above-described sealing structure 60, the same reference numerals will be used and detailed description thereof will be omitted.

[0045] In the sealing structure 70, a second groove portion 63 communicating with the first gap G1 is provided in the second contact surface 52C of the upper housing 52. The width of the second groove portion 63 may be the same as the width of the first gap G1. The outer wall portion 63B of the second groove portion 63 and the wall portion 61B of the first groove portion 61 may be at the same position in the width direction. Also, the inner wall portion 63C of the second groove portion 63 and the wall portion 62B of the protrusion 62 may be continuously formed.

[0046] According to the second groove portion 63, at the time of sealing, a space for the liquid gasket 65 to rise toward the first gap G1 can be secured. Thereby, when the first gap G1 is filled with the liquid gasket 65, it is possible to suppress the liquid gasket 65 from flowing into the second gap G2. As a result, it is possible to suppress variations in the rise of the liquid gasket 65 in the gap G.

[0047] [Summary] The present invention is further described by the following embodiments. Configuration 1: A storage module comprising a plurality of energy storage devices, a holder for holding the plurality of energy storage devices, and a housing for housing the holder, wherein the housing includes a first housing and a second housing arranged in a first direction, the first housing and the second housing are sealed by a sealing structure, the sealing structure having a first groove provided on the first contact surface of the first housing with the second housing, a ridge-shaped projection provided on the second contact surface of the second housing with the first housing and housed in the first groove, and a liquid gasket provided between the first groove and the projection, the center of the first groove and the center of the projection are offset in a second direction perpendicular to the first direction. Configuration 2: The storage module according to Configuration 1, wherein in the second direction, the center of the first groove is offset to one side from the center of the projection. Configuration 3: A power storage module according to Configuration 1, wherein the gap between the first groove and the projection includes a first gap located on one side and a second gap located on the other side in a second direction perpendicular to the first direction, and the width of the first gap in the second direction is greater than the width of the second gap. Configuration 4: A power storage module according to Configuration 3, wherein the second contact surface of the second housing is provided with a second groove that communicates with the first gap. Configuration 5: A power storage module according to any one of Configurations 2 to 4, wherein the first contact surface has a pair of first regions arranged to sandwich the first groove in the second direction, and the second contact surface has a pair of second regions arranged to sandwich the projection in the second direction. Configuration 6: A power storage module according to any one of Configurations 1 to 4, wherein the first housing has a plate-shaped first base and an annular first wall extending from the first base in a first direction, and the first contact surface is provided on the first wall; and the second housing has a plate-shaped second base and an annular second wall extending from the second base in a first direction, and the second contact surface is provided on the second wall.

[0048] Note that the present disclosure is not limited to the above-described embodiments and their modified examples, and it is needless to say that various changes and improvements can be made within the scope of the matters described in the claims of the present application.

[0049] 10 Power storage module, 20 Power 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 lead, 28 Negative electrode lead, 29 Gasket, 30 Insulating plate, 40 Holder, 41 Lower holder, 42 Upper holder, 43 Accommodating portion, 44 Accommodating portion, 50 Housing, 51 Lower housing, 51A Base portion, 51B Wall portion, 51C First contact surface, 51D First region, 52 Upper housing, 52A Base portion, 52B Wall portion, 52C Second contact surface, 52D Second region, 60, 70 Sealing structure, 61 First groove portion, 61A Bottom surface, 61B Wall portion, 62 Protrusion, 62B Wall portion, 63 Second groove portion, 63B Outer wall portion, 63C Inner wall portion, 65 Liquid gasket, G Gap, G1 First gap, G2 Second gap

Claims

1. An energy storage module comprising a plurality of energy storage devices, a holder for holding the plurality of energy storage devices, and a housing for housing the holder, wherein the housing includes a first housing and a second housing arranged in a first direction, the first housing and the second housing are sealed by a sealing structure, the sealing structure having a first groove provided on the first contact surface of the first housing with the second housing, a ridge-shaped projection provided on the second contact surface of the second housing with the first housing and housed in the first groove, and a liquid gasket provided between the first groove and the projection, the center of the first groove and the center of the projection are offset in a second direction perpendicular to the first direction.

2. An energy storage module according to claim 1, wherein in the second direction, the center of the first groove is offset to one side from the center of the protrusion.

3. The energy storage module according to claim 1, wherein the gap between the first groove and the projection includes a first gap located on one side in a second direction perpendicular to the first direction and a second gap located on the other side, and the width of the first gap in the second direction is greater than the width of the second gap.

4. An energy storage module according to claim 3, wherein the second contact surface of the second housing is provided with a second groove that communicates with the first gap.

5. A power storage module according to any one of claims 2 to 4, wherein the first contact surface has a pair of first regions arranged in the second direction to sandwich the first groove, and the second contact surface has a pair of second regions arranged in the second direction to sandwich the protrusion.

6. A power storage module according to any one of claims 1 to 4, wherein the first housing has a plate-shaped first base and an annular first wall extending from the first base in a first direction, and the first contact surface is provided on the first wall; and the second housing has a plate-shaped second base and an annular second wall extending from the second base in a first direction, and the second contact surface is provided on the second wall.

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