Power storage module

Abstract

Provided is a power storage module (10) that includes at least one cylindrical power storage device (20), wherein a shoulder part (25B) of an outer can (25) that serves as a negative electrode terminal is provided at an upper end in a first direction of the power storage device (20), a negative electrode lead (42) that extends in a second direction that is orthogonal to the first direction is connected to the shoulder part (25B), and pressing members (56) that extend in the second direction are provided to urge the negative electrode lead (42) toward the shoulder part (25B). At least two pressing members (56) are provided for each negative electrode lead (42).

Description

Power storage module

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

[0002] The power storage module has at least one cylindrical power storage device. For example, Patent Document 1 discloses a power storage module having a plurality of cylindrical power storage devices, provided with a positive electrode terminal and a negative electrode terminal at the upper end of the power storage device, and a positive electrode lead and a negative electrode lead are respectively connected to the positive electrode terminal and the negative electrode terminal.

[0003] International Publication No. 2019 / 058938

[0004] The above-described power storage module is widely used as a power source for electric equipment, and high reliability is required.

[0005] Therefore, an object of the present disclosure is to provide a power storage module capable of improving reliability.

[0006] The power storage module according to the present disclosure is a power storage module having at least one cylindrical power storage device, wherein at least one terminal is provided at one end of the power storage device in the first direction, and a lead extending in the second direction orthogonal to the first direction is connected to the terminal, and it has a pressing member extending in the second direction and biasing the lead toward the terminal.

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

[0008] It is a schematic diagram showing a power storage module which is an example of an embodiment. It is a schematic diagram showing a power storage device. It is a plan view showing a pressing member. It is a perspective view showing a pressing member. It is another perspective view showing a pressing member. It is a schematic diagram showing a power storage module which is another example of an embodiment.

[0009] Hereinafter, an example of an embodiment of the present disclosure will be described in detail. In the following description, specific shapes, materials, directions, numerical values, etc. are examples for facilitating the understanding of the present disclosure, and can be appropriately changed according to applications, purposes, specifications, etc.

[0010] [Power storage module] The power storage module 10 which is an example of an embodiment will be described using FIG. 1.

[0011] 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.

[0012] As will be explained in more detail later, the energy storage module 10 can improve the reliability of the energy storage device 20. In the following explanation, each component may be described using the upper or lower axial side of the energy storage device 20 housed in the energy storage module 10.

[0013] Each energy storage module 10 comprises a plurality of energy storage devices 20, each of which will be described in detail later, a current collector plate 40 that collects current from the energy storage devices 20, and a holder (upper holder 50) that holds the plurality of energy storage devices 20.

[0014] Multiple energy storage devices 20 may be packed as tightly 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 may be arranged such that the closest energy storage devices are placed on each of the four sides.

[0015] [Energy Storage Device] The energy storage device 20 according to the embodiment will be described with reference to Figure 2.

[0016] 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 at one end of the outer container 25 in a first direction while insulating it, 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.

[0017] 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.

[0018] 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 is configured on the top surface of the sealing body 26, and the negative electrode terminal is configured on the crimped shoulder portion 25B of the outer casing 25.

[0019] [Current Collector Plate] An example of an embodiment, the current collector plate 40, will be described using Figures 1, 3 to 5.

[0020] The current collector plate 40 is provided on the upper surface of the upper holder 50, which will be described later. The current collector plate 40 is made of a conductive metal plate. The current collector plate 40 has a positive lead 41 connected to the positive terminal of the energy storage device 20, a negative lead 42 connected to the negative terminal of the energy storage device 20, and a current collector plate body 43 to which the positive lead 41 and the negative lead 42 are connected. In this embodiment, the series end of the energy storage module 10 includes a current collector plate having only the positive lead 41 and a current collector plate having only the negative lead 42.

[0021] In the following, the direction in which the positive lead 41 or negative lead 42 extends may be described as the second A direction (arrow W in the figure) which is perpendicular to the first direction, and the direction perpendicular to the first direction and the second A direction in a plan view may be described as the second B direction (arrow D in the figure).

[0022] In this embodiment, all current collector plates 40 are arranged on the upper surface of the upper holder 50, but the disclosure is not limited thereto. The disclosure may also include a configuration in which the current collector plates arranged on the upper surface of the upper holder are connected to one terminal of the energy storage device, and the current collector plates arranged on the bottom surface of the lower holder are connected to the other terminal of the energy storage device.

[0023] The positive lead 41 is connected to a sealing body 26 (positive terminal) exposed through an opening 53 of the upper holder 50, which will be described later. The positive lead 41 has a connecting portion 41A that is joined to the sealing body 26, and a lead connecting portion 41B that connects the connecting portion 41A to the current collector plate body 43.

[0024] The negative electrode lead 42 is connected to the shoulder portion 25B of the outer casing 25, which is exposed through the opening 54 of the upper holder 50, which will be described later. The negative electrode lead 42 has a joint portion 42A that is joined to the shoulder portion 25B of the outer casing 25, and a lead connection portion 42B that connects the joint portion 42A to the current collector plate body 43. The positive electrode lead 41 and the negative electrode lead 42 may be integrated with the current collector plate body 43, or they may be joined to other conductive parts.

[0025] Here, during high-rate discharge of the energy storage device 20, Joule heating is high, and the current path generates heat. In particular, the shoulder portion 25B of the outer casing 25 generates a high amount of heat. Furthermore, there is contact thermal resistance between the joint portion 41A of the positive lead 41 and the sealing body 26 (positive terminal), or between the joint portion 42A of the negative lead 42 and the shoulder portion 25B of the outer casing 25 (negative terminal) (hereinafter, between the joint portion and the terminal). Therefore, in order to reduce the heat generated in the current path during high-rate discharge of the energy storage device 20, it is necessary to reduce the contact thermal resistance between the joint portion and the terminal.

[0026] Therefore, as explained below, by biasing the joint toward the terminals of the energy storage device 20 with a retaining member, poor contact between the two components at the time of joining the joint and the terminal is improved, and stress in the first direction after connection is also reduced, thereby reducing the contact thermal resistance between the joint and the terminal.

[0027] [Holder] An example of a holder, which is part of an embodiment, will be described using Figures 1, 3 to 5.

[0028] The holder holds the energy storage device 20. The holder is divided vertically into an upper holder 50 and a lower holder (not shown). If the holder 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 upper holder 50 and the lower holder are fixed to each other via a fixing member or using locking parts provided on each holder.

[0029] A current collector plate 40 for collecting current from the energy storage device 20 is provided on the upper surface of the upper holder 50. The upper holder 50 has a housing section 51, an opening 53, an opening 54, a pair of retaining members 55, and a pair of retaining members 56, which will be described in detail later. The housing section 51 is formed as a cylindrical recess in which the upper portion of each energy storage device 20 is housed.

[0030] The opening 53 is located on the upper surface of the upper holder 50 and is formed to open in a circular shape in the center of the upper surface of the housing 51. As a result, the sealing body 26 (positive terminal) of the energy storage device 20 is exposed through the opening 53. In addition, the opening 53 is provided with a pair of retaining members 55 that extend along the second direction from the end in the second direction at the edge of the opening 53.

[0031] The opening 54 is located on the upper surface of the upper holder 50 and is formed on one side of the opening 53 in the first direction, opening a rectangular portion of the upper surface of the housing 51. This exposes the shoulder portion 25B (negative terminal) of the outer casing 25 of the energy storage device 20 through the opening 54. The opening 54 is also provided with a pair of retaining members 56 extending along the second direction from the end in the second direction at the edge of the opening 54. The opening 53 and the opening 54 may be formed separately from each other, or they may be connected to form a single opening.

[0032] The pair of pressing members 55 are formed in a tongue shape and extend from their ends in the second direction along the second B direction at the edge of the opening 53. Each pressing member 55 has a pressing portion 55A that presses the joint portion 41A of the positive lead 41 in the first direction, and a pressing connecting portion 55B which is a base portion that connects the pressing portion 55A and the edge of the opening 53.

[0033] Here, the retaining member 55 is formed such that when the energy storage device 20 is not housed in the housing portion 51 of the upper holder 50, the retaining portion 55A is positioned below the upper surface position of the housing portion 51. Therefore, when the energy storage device 20 is housed in the housing portion 51 of the upper holder 50, the retaining member 55 is pushed up by the sealing body 26 of the energy storage device 20. At this time, the positive electrode lead 41 is biased toward the sealing body 26 in the first direction by the reaction force when the sealing body 26 pushes up the retaining member 55. In other words, the positive electrode lead 41 is biased toward the sealing body 26 by the retaining member 55.

[0034] This reduces the contact thermal resistance between the joint 41A and the sealing body 26. As a result, heat generation in the current path during high-rate discharge of the energy storage device 20 can be reduced. This improves the reliability of the energy storage module 10.

[0035] The pair of retaining members 55 bias each end of the joint portion 41A of the positive lead 41 in the second B direction. This allows the joint portion 41A to be biased evenly toward the sealing body 26. As a result, the contact thermal resistance between the joint portion 41A and the sealing body 26 can be reliably reduced.

[0036] Furthermore, in the manufacturing process of the energy storage device 20, a pressing jig is used to press the joint 41A toward the sealing body 26 when welding the joint 41A to the sealing body 26. In this embodiment, however, the pressing jig can be made unnecessary by biasing each end of the joint 41A in the second direction with a pair of pressing members 55. However, this does not necessarily mean that the energy storage module of this disclosure does not require the use of a pressing jig.

[0037] The retaining connection portion 55B does not overlap with the lead connection portion 41B in a plan view. More specifically, in the opening 53, the retaining connection portion 55B is arranged along the second B direction, and the lead connection portion 41B is arranged along the second A direction, which is different from the second B direction, so they do not overlap. In other words, in the direction in which the positive electrode lead 41 extends, the region of the positive electrode lead 41 on the current collector plate body 43 side is exposed from the retaining member 55 in the first direction. In this embodiment, the retaining connection portion 55B is arranged along the second direction, but this disclosure is not limited to this. This disclosure is acceptable as long as the retaining connection portion does not overlap with the lead connection portion.

[0038] In this configuration, where the retaining connector overlaps with the lead connector, the retaining connector and the lead connector overlap at the opening that serves as the exhaust path in the event of an unsafe situation with the energy storage device. Therefore, there is a risk that either the retaining connector or the lead connector may remain in the exhaust path during exhaust. Furthermore, in this configuration, where the retaining connector overlaps with the lead connector, the height of the upper holder increases, which may reduce the energy density of the energy storage module.

[0039] In this embodiment, since the retaining connection portion 55B and the lead connection portion 41B do not overlap, when an unsafe situation occurs in the energy storage device, neither the retaining connection portion 55B nor the lead connection portion 41B remains in the exhaust path during exhaust. This improves the reliability of the energy storage module. Furthermore, in this embodiment, since the retaining connection portion 55B and the lead connection portion 41B do not overlap, the energy density can be improved compared to a configuration in which the retaining connection portion overlaps with the lead connection portion.

[0040] The pair of pressing members 56 are formed in a tongue shape and extend along the second B direction from their ends in the second B direction at the edge of the opening 54. Each pressing member 56 has a pressing portion 56A that presses against the joint portion 42A of the negative electrode lead 42, and a pressing connecting portion 56B that connects the pressing portion 56A to the edge of the opening 54.

[0041] Here, the retaining member 56 is formed such that when the energy storage device 20 is not housed in the housing portion 51 of the upper holder 50, the retaining portion 56A is positioned below the upper surface of the housing portion 51. Therefore, when the energy storage device 20 is housed in the housing portion 51 of the upper holder 50, the retaining member 56 is pushed up by the shoulder portion 25B of the outer casing 25 of the energy storage device 20. At this time, the negative electrode lead 42 is biased toward the shoulder portion 25B in the first direction by the reaction force when the shoulder portion 25B pushes up the retaining member 56. In other words, the negative electrode lead 42 is biased toward the shoulder portion 25B by the retaining member 56.

[0042] This reduces the contact thermal resistance between the joint 42A and the shoulder portion 25B. As a result, heat generation in the current path during high-rate discharge of the energy storage device 20 can be reduced. This improves the reliability of the energy storage module 10.

[0043] The pair of pressing members 56 biases the respective ends of the joint portion 42A in the second direction. As a result, the joint portion 42A can be biased without bias toward the shoulder portion 25B of the outer can 25. As a result, the contact thermal resistance between the joint portion 42A and the shoulder portion 25B can be reliably reduced. Further, when welding the joint portion 42A and the shoulder portion 25B, a pressing jig can be made unnecessary.

[0044] The pressing connection portion 56B does not overlap with the lead connection portion 42B in a plan view. That is, in the direction in which the negative electrode lead 42 extends, the region on the current collector body 43 side of the negative electrode lead 42 is exposed from the pressing member 56 in the first direction. More specifically, in the opening 54, the pressing connection portion 56B is arranged along the second B direction, and the lead connection portion 42B is arranged along the second A direction, so that the two do not overlap. In the present embodiment, the pressing connection portion 56B is arranged along the second B direction, but the present disclosure is not limited to this. The present disclosure may be any configuration in which the pressing connection portion does not overlap with the connection portion.

[0045] As a result, for the same reason as the pressing connection portion 55B, the reliability of the power storage module 10 can be improved. Further, the energy density can be improved as compared with a configuration in which the pressing connection portion 56B overlaps with the lead connection portion 42B.

[0046] A plurality of accommodating portions, which are columnar depressions in which the lower portions of the respective power storage devices 20 are accommodated, are formed in the lower holder. A current collector plate for collecting current from the power storage device 20 may be provided on the lower surface of the lower holder. In this case, each of the plurality of accommodating portions is formed with an opening that forms an opening on the lower surface of the lower holder, and a plurality of leads of the current collector plate are inserted through the opening, and the leads may be connected to the sealing body 26 or the shoulder portion 25B of the outer can 25.

[0047] In the present embodiment, the pressing members 55 and 56 are provided as the pressing members, but the present disclosure is not limited to this. In the present disclosure, since the heat generation of the shoulder portion 25B of the outer can 25 is particularly high among the current conduction paths of the power storage device 20, a configuration in which only the pressing member 56 is provided as the pressing member may be employed.

[0048] [Other Embodiments] A power storage module 110, which is another example of an embodiment, will be described with reference to FIG. 6. Hereinafter, members different from those in the above-described embodiment will be described, and members the same as those in the above-described embodiment will be denoted by the same reference numerals as those in the above-described embodiment, and detailed description thereof will be omitted.

[0049] The power storage module 110 includes a plurality of power storage devices 20, a current collecting plate 40 that collects current from the power storage devices 20, a holder (upper holder 50) that holds the plurality of power storage devices 20, and an insulating plate 60 disposed on the current collecting plate. The insulating plate 60 is formed with a pair of pressing members (not shown) for pressing the positive electrode lead and a pair of pressing members 62 for pressing the negative electrode lead 42. Since these pressing members have the same configuration and effects as the pressing members 55 and 56 of the above-described upper holder 50, description thereof will be omitted.

[0050] [Summary] The present invention is further described by the following embodiments. Configuration 1: A storage module having at least one cylindrical energy storage device, wherein at least one terminal is provided at one end of the energy storage device in a first direction, a lead extending in a second direction perpendicular to the first direction is connected to the terminal, and a pressing member extending in the second direction biases the lead toward the terminal. Configuration 2: The storage module according to Configuration 1, wherein at least two pressing members are provided for one lead. Configuration 3: The storage module according to Configuration 1, wherein the pressing member has a pressing portion that presses the lead toward the terminal, and a non-opposing portion that does not overlap with the lead in the first direction, wherein in the direction in which the lead extends, the non-opposing portion is further from the tip of the pressing member than the pressing portion, and the lead has the non-opposing portion in a region further from the tip of the lead than the portion that overlaps with the pressing portion in the first direction. Configuration 4: A power storage module according to Configuration 3, wherein the lead has a joint portion joined to the terminal, and the pressing portion presses the edge of the joint portion. Configuration 5: A power storage module according to Configuration 1, wherein the holder holds the axial direction of the power storage device, and the pressing member is part of the holder. Configuration 6: A power storage module according to Configuration 5, wherein the holder has an opening that exposes the terminal, the pressing member is formed in the shape of a tongue protruding from the edge of the opening toward the opening, and the connection portion of the pressing member with the opening does not overlap with the lead. Configuration 7: A power storage module according to Configuration 1, wherein the current collector plate connected to the lead and the current collector plate are insulated, and the pressing member is part of the insulating plate.Configuration 8: A power storage module according to Configuration 7, comprising a holder that holds the axial direction of the power storage device, the holder having an opening that exposes the terminals, the retaining member being formed in the shape of a tongue protruding toward the opening, and the connection portion of the retaining member with the opening not overlapping with the lead.

[0051] It should be noted that this disclosure 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.

[0052] 10, 110 Energy storage module, 20 Energy storage device, 21 Positive electrode, 22 Negative electrode, 23 Separator, 24 Electrode group, 25 Outer casing, 25A Groove, 25B Shoulder (negative electrode terminal), 26 Sealing body (positive electrode terminal), 27 Positive electrode tab, 28 Negative electrode tab, 29 Gasket, 30 Insulating plate, 40 Current collector plate, 41 Positive electrode lead, 41A Joint, 41B Lead connection, 42 Negative electrode lead, 42A Joint, 42B Lead connection, 50 Upper holder (Holder), 51 Housing section, 53 Opening, 54 Opening, 55 Retaining member, 55A Retaining section, 55B Retaining connection, 56 Retaining member, 56A Retaining section, 56B Retaining connection, 60 Insulating plate, 61 Retaining member

Claims

1. An energy storage module having at least one cylindrical energy storage device, wherein at least one terminal is provided at one end of the energy storage device in a first direction, a lead extending in a second direction perpendicular to the first direction is connected to the terminal, and a retaining member extending in the second direction biases the lead toward the terminal.

2. The energy storage module according to claim 1, wherein at least two of the retaining members are provided for one of the leads.

3. An energy storage module according to claim 1, wherein the retaining member has a retaining portion that presses the lead toward the terminal and a non-opposing portion that does not overlap with the lead in the first direction, the non-opposing portion is further from the tip of the retaining member than the retaining portion in the direction in which the lead extends, and the lead has the non-opposing portion in a region that is further from the tip of the lead than the portion that overlaps with the retaining portion in the first direction in the direction in which the lead extends.

4. An energy storage module according to claim 3, wherein the lead has a joint portion joined to the terminal, and the retaining portion presses the edge of the joint portion.

5. An energy storage module according to claim 1, comprising a holder that holds the energy storage device in the axial direction, wherein the retaining member is part of the holder.

6. A power storage module according to claim 5, wherein the holder has an opening for exposing the terminals, the retaining member is formed in the shape of a tongue protruding from the edge of the opening toward the opening, and the connection portion of the retaining member with the opening does not overlap with the lead.

7. An energy storage module according to claim 1, comprising a current collector plate connected to the lead and an insulating plate that insulates the current collector plate, wherein the retaining member is a part of the insulating plate.

8. An energy storage module according to claim 7, comprising a holder that holds the energy storage device in an axial direction, the holder having an opening that exposes the terminals, the retaining member being formed in the shape of a tongue protruding toward the opening, and the connection portion of the retaining member with the opening not overlapping with the lead.

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