Battery pack and method for manufacturing battery pack

Abstract

Provided are a battery pack in which a plurality of columnar batteries are housed, an exhaust path is secured, and spaces between components are sealed, and a method for manufacturing the battery pack. A battery pack (1) for housing a plurality of columnar batteries (22) is provided with: a first battery holder (10) including a plurality of first recessed portions (20) in which one end portions of the batteries (22) are fitted and which hold the plurality of batteries (22) such that the adjacent batteries are separated from each other; and a second battery holder (12) including a plurality of second recessed portions (30) in which the other end portions of the batteries (22) are fitted. The bottom portion of each of the first recessed portions (20) is provided with at least one through hole (26), a current collector plate (36) for electrically connecting the plurality of batteries (22) to each other is disposed through the through hole (26), the gaps between the first recessed portions (20) and the batteries (22) are sealed with a sealing portion (28), and the sealing portion (28) is in the same plane as that of the current collector plate (36) or inward of the same plane.

Description

Battery pack and method for manufacturing battery pack

[0001] The present disclosure relates to a battery pack and a method for manufacturing a battery pack, and particularly to a battery pack housing a plurality of columnar batteries and a method for manufacturing the same.

[0002] Batteries are widely used as power sources for various electronic devices and the like. Types of batteries include primary batteries typified by dry batteries, and secondary batteries such as lithium ion secondary batteries that can be repeatedly charged and discharged. These batteries have various shapes including columnar shapes such as cylindrical and prismatic shapes, and sheet shapes, and columnar batteries are the most common.

[0003] Generally, lithium ion batteries are used in the form of a battery pack in which a plurality of batteries are electrically connected and housed in a container. As a cooling method for battery packs, there is a method called immersion cooling in which the inside of the pack is filled with an insulating cooling liquid. Immersion cooling includes a full-immersion type in which the entire inside of the pack is filled with cooling liquid, and a partial-immersion type in which the cooling liquid can be held at required locations inside the pack. While the partial-immersion type has the advantage of reducing the amount of cooling liquid and reducing the weight of the battery pack, it requires a structure for sealing between components to retain the cooling liquid in specific locations. In particular, when cooling batteries with the partial-immersion type, it is necessary to have a structure in which cooling liquid is put into a battery holder that holds the batteries and sealed to prevent liquid from leaking from the battery holder.

[0004] As a sealing structure for filling the gap between a battery holder and a battery, Patent Document 1 discloses a configuration in which one end and the other end of the battery are filled and sealed with potting resin (see FIG. 5 of Patent Document 1).

[0005] Japanese National Publication of International Patent Application No. 2023-531640

[0006] Lithium-ion batteries generally have an exhaust valve to release pressure when the internal pressure of the battery rises. Therefore, if one end and the other end of the battery holder are filled with potting resin, as in the configuration of Patent Document 1, there is a high risk of obstructing exhaust from inside the battery. Furthermore, although Patent Document 1 has a configuration in which the potting resin is broken to form an exhaust hole so that exhaust can be released from inside the battery, this has the problem that the exhaust space of the battery pack becomes larger in order to secure space for exhaust, and the volumetric energy density decreases.

[0007] The object of this disclosure is to provide a battery pack containing multiple columnar batteries, in which an exhaust path is secured and the components are sealed together, and a method for manufacturing the battery pack.

[0008] This disclosure relates to a battery pack for housing a plurality of columnar batteries, comprising: a first battery holder having a plurality of first recesses into which one end of each battery fits and which holds the plurality of batteries apart from adjacent batteries; and a second battery holder having a plurality of second recesses into which the other end of each battery fits, wherein at least one through hole is provided at the bottom of each first recess, a current collector plate for electrically connecting the plurality of batteries is arranged through the through hole, and the gap between the first recess and the batteries is sealed by a sealing portion, the sealing portion being in the same plane as or inside the same plane as the current collector plate.

[0009] This disclosure relates to a method for manufacturing a battery pack that houses a plurality of columnar batteries, wherein the battery pack comprises a first battery holder having a plurality of first recesses into which one end of the batteries fits and the plurality of batteries are held such that adjacent batteries are spaced apart, and a second battery holder having a plurality of second recesses into which the other end of the batteries fits, wherein at least one through hole is provided at the bottom of the first recess, and the method includes the step of holding one end of the batteries in the first recess, arranging a current collector plate for electrically connecting the plurality of batteries through the through hole, and then flowing a sealing material into the gap between the batteries and the first recess to form a sealing portion in the gap between the first recess and the batteries and sealing, wherein the sealing portion is in the same plane as or inside the same plane as the current collector plate.

[0010] This disclosure provides a battery pack containing multiple columnar batteries, in which an exhaust path is secured and the components are sealed together, and a method for manufacturing the battery pack.

[0011] This is a schematic diagram showing an example of a battery pack according to the embodiment of this disclosure. This is a schematic diagram showing an example of a sealing structure and a method for manufacturing the same in a battery pack according to the embodiment of this disclosure. This is a schematic diagram showing another example of a sealing structure and a method for manufacturing the same in a battery pack according to the embodiment of this disclosure. This is a schematic diagram showing another example of a sealing structure and a method for manufacturing the same in a battery pack according to the embodiment of this disclosure.

[0012] Embodiments of this disclosure will be described below. These embodiments are examples of implementing this disclosure, and this disclosure is not limited to these embodiments.

[0013] The battery pack according to this embodiment comprises multiple columnar batteries electrically connected and housed in a container, for example, multiple cylindrical lithium-ion secondary batteries housed in the container. These batteries are cylindrical in shape, with one end being, for example, a negative electrode and the other end being, for example, a positive electrode.

[0014] The battery pack according to this embodiment employs a liquid immersion cooling method in which the inside of the battery pack is filled with an insulating coolant. In particular, it employs a partial immersion type liquid immersion cooling method that allows the coolant to be retained in the necessary locations within the battery pack. The partial immersion type has the advantage of reducing the amount of coolant and thus reducing the weight of the battery pack.

[0015] Hereinafter, embodiments of the battery pack and its manufacturing method according to this disclosure will be described in detail with reference to the drawings.

[0016] It is intended from the outset that new embodiments can be constructed by appropriately combining the characteristic features of the embodiments and modifications described below. In the following embodiments, the same reference numerals are used for the same components in the drawings, and redundant explanations are omitted. In addition, multiple drawings include schematic diagrams, and the dimensional ratios such as length, width, and height of each component do not necessarily match between different drawings. Furthermore, among the components described below, components that are not described in the independent claim indicating the highest-level concept are optional components and are not essential components. Moreover, this disclosure is not limited to the embodiments and modifications described below, and various improvements and changes are possible within the scope of the claims of this application and to an equal extent.

[0017] Figure 1 is a schematic diagram showing an example of a battery pack according to this embodiment. Figure 1 is a diagram showing the battery pack according to this embodiment from the side, with the inside visible.

[0018] The battery pack 1 shown in Figure 1 is a battery pack that houses a plurality of columnar batteries 22. The battery pack 1 comprises a first battery holder 10 having a plurality of first recesses 20 into which one end of each battery 22 fits and which holds the plurality of batteries 22 apart from each other, and a second battery holder 12 having a plurality of second recesses 30 into which the other end of each battery 22 fits.

[0019] The first battery holder 10 is, for example, a rectangular plate-shaped member and comprises a plurality of first recesses 20 in which a plurality of batteries 22 are held such that adjacent batteries are spaced apart, and at least one through hole 26 is provided at the bottom of the first recess 20. There are no particular restrictions on the arrangement position or number of the first recesses 20 in the first battery holder 10.

[0020] As shown in Figure 1, a current collector plate 36 for electrically connecting multiple batteries 22 is positioned through a through hole 26 provided in the first recess 20, and the gap between the first recess 20 and the batteries 22 is sealed by a sealing portion 28.

[0021] One end of each of the multiple batteries 22 is fitted into the first recess 20 of the first battery holder 10, and the other end is fitted into the second recess 30 of the second battery holder 12. In this way, both ends of the battery 22 are fitted into the first recess 20 and the second recess 30. As a result, each battery 22 is fixed and held in place by the first recess 20 of the first battery holder 10 and the second recess 30 of the second battery holder 12. In this manner, each of the multiple batteries 22 is fixed and held apart from the adjacent battery 22 (with a certain distance between their sides), and they stand in a nearly vertical line.

[0022] The first battery holder 10 and the second battery holder 12, each holding multiple batteries 22, are housed in a box-shaped casing 14, for example, which has a bottom surface but no top surface, and the upper opening is covered by a top plate 16. The first battery holder 10 and the second battery holder 12 may be housed in a box-shaped casing 14 that has no top surface and no bottom surface, and the upper opening may be covered by a top plate 16, or they may be housed in a box-shaped casing 14 that has a top surface and a bottom surface. A cavity 24 is provided above the first battery holder 10 inside the casing 14. The upper opening of the casing 14 may be covered by a lid member 38, which will be described later, instead of a top plate 16.

[0023] The space between the batteries 22 inside the first battery holder 10 and the second battery holder 12 is filled with an insulating coolant 32. The coolant 32 may be introduced through piping or the like from a coolant inlet 18 that connects the inside of the first battery holder 10 and the second battery holder 12 of the battery pack 1 with the outside of the battery pack 1, and discharged from a coolant outlet 19.

[0024] In order to retain the coolant inside the first battery holder 10 and the second battery holder 12, in addition to the sealing portion 28 between the first recess 20 of the first battery holder 10 and the battery 22, the battery pack 1 is sealed by a sealing portion 33 provided at the connection between the first battery holder 10 and the second battery holder 12, a sealing portion 34 provided at the connection between the second battery holder 12 and the coolant inlet 18, and a sealing portion 35 provided at the connection between the second battery holder 12 and the coolant outlet 19. This creates a sealed structure that prevents coolant from leaking out of the battery pack 1.

[0025] Figures 2 to 4 are schematic diagrams showing an example of a sealing structure in a battery pack according to the present disclosure and a method for manufacturing the same.

[0026] As shown in Figure 2, one end of the battery 22 is held in the first recess 20 of the first battery holder 10, and a current collector plate 36 for electrically connecting the multiple batteries 22 is placed through the through hole 26. Next, a sheet material 42 with high thermal shrinkage properties is installed so as to cover the sealing surface of the first battery holder 10, that is, so as to cover the current collector plate 36 and the through hole 26. Then, a sealing material 40 is poured in through the gap between the battery 22 and the first recess 20 and fixed in place, forming a sealing portion 28 in the gap between the first recess 20 and the battery 22 to seal it. When the sealing material 40 is poured in, a lid member 38 may be placed on the side opposite to the side in the first recess 20 of the first battery holder 10 where one end of the battery 22 is held, such that the lid portion covers the through hole 26 at a predetermined distance. The lid member 38 creates a space between the sheet material 42 and the inner surface of the lid member 38. By installing the sheet material 42, the sealing portion 28 is located in the same plane as or inside the same plane as the outer surface of the current collector plate 36 (on the side where the battery 22 is held), and the surface of the sealing portion 28 is aligned with the outer surface of the current collector plate 36 (the opposite side of the side where one end of the battery 22 in the first recess 20 is held). As a result, the battery 22 has an exhaust valve on one end side to release pressure from inside the battery when the internal pressure of the battery rises, and even when exhaust occurs, the heat of the exhaust melts the sealing portion 28 and the sheet material 42, ensuring an exhaust space. In this way, the upper and lower surfaces of the first battery holder 10 can be sealed while ensuring an exhaust path for the battery pack 1.

[0027] As shown in Figure 3, one end of the battery 22 is held in the first recess 20 of the first battery holder 10, and a current collector plate 36 for electrically connecting multiple batteries 22 is positioned through the through hole 26. Next, a thick sheet material 44 with high thermal shrinkage is installed so as to cover the sealing surface of the first battery holder 10, that is, so as to cover the current collector plate 36 and the through hole 26. Then, a sealing material 40 is allowed to flow in from the gap between the battery 22 and the first recess 20 to form a sealing portion 28 in the gap between the first recess 20 and the battery 22 and seal it. A lid member 38 may be positioned on the side opposite to the side in the first recess 20 of the first battery holder 10 where one end of the battery 22 is held, such that the lid portion covers the through hole 26 at a predetermined distance. The sealing portion 28 is in the same plane as the outer surface of the current collector plate 36 or inside the same plane (on the side where the battery 22 is held), and the outer surface of the current collector plate 36 and the surface of the sealing portion 28 are aligned. As a result, even if the battery 22 has an exhaust valve on one end and exhausts air, the heat from the exhaust melts the sealing portion 28 and the sheet material 44, ensuring an exhaust space. In this way, the upper and lower surfaces of the first battery holder 10 can be sealed while maintaining the exhaust path of the battery pack 1.

[0028] As shown in Figure 4, one end of the battery 22 is held in the first recess 20 of the first battery holder 10, and a current collector plate 36 for electrically connecting multiple batteries 22 is positioned through the through hole 26. Next, a release member 46 having a protrusion is placed so as to cover the sealing surface of the first battery holder 10, i.e., the current collector plate 36 and the through hole 26, with the protrusion fitting into the through hole 26 of the first battery holder 10. After that, a sealing material 40 is poured in through the gap between the battery 22 and the first recess 20 to form a sealing portion 28 in the gap between the first recess 20 and the battery 22 and seal it. After the sealing material 40 has hardened, the release member 46 is removed. After removing the release member 46, a lid member 38 may be positioned on the side of the first recess 20 of the first battery holder 10 opposite to the side where one end of the battery 22 is held, such that the lid portion covers the through hole 26 at a predetermined distance. The lid member 38 creates a space between the outer surface of the current collector plate 36 and the inner surface of the lid member 38. The sealing portion 28 is configured such that its surface is formed inward from the coplane with the outer surface of the current collector plate 36 at the through hole 26 of the first battery holder 10 (on the side where the battery 22 is held). As a result, even if the battery 22 has an exhaust valve on one end and exhausts, the heat of the exhaust melts the sealing portion 28, ensuring an exhaust space. In this way, the upper and lower surfaces of the first battery holder 10 can be sealed while ensuring the exhaust path of the battery pack 1. The upper and lower surfaces of the first battery holder 10 can be sealed while ensuring not only the exhaust space of the battery pack 1 but also the exhaust space immediately adjacent to the exhaust valve of the battery 22. Instead of the release member 46 having a protrusion, the same configuration as in Figure 4 can be achieved by flowing the sealing material 40 into the through hole 26 of the first battery holder 10 and pressing the release member 46 against it. This configuration ensures that the surface of the sealing portion 28 is located inward from the first battery holder 10 in the through hole 26 of the first battery holder 10. In addition, it is desirable that a sealing portion 28 be formed in which the sealing material 40 is filled along the end face of the battery 22 and the outer surface of the current collector plate 36. This is achieved by a release member 46 having a protrusion.

[0029] In the method for manufacturing the battery pack according to this embodiment, after placing the battery 22 in the first battery holder 10 and attaching the current collector plate 36, with the first battery holder 10 in the lower position, the sealing material 40 is poured in from the side of the first battery holder 10 where the battery 22 is placed, applied, and fixed, thereby sealing the space between the battery 22 and the first battery holder 10 after assembling the current collector plate 36.

[0030] The shape of the first recess 20 is, for example, a shape that conforms to the outer diameter of the battery 22. For example, if the cylindrical battery to be housed has a circular outer diameter, the shape of the first recess 20 may be a circular shape that conforms to the circular outer diameter of the battery. If the battery to be housed is a rectangular prism, the shape of the first recess 20 may be a rectangular shape that conforms to the rectangular outer diameter of the rectangular prism battery.

[0031] The first recess 20 has a shape equivalent to the outer diameter of the battery 22. The gap between the inner wall of the first recess 20 and the side surface of the battery 22 should be large enough to allow one end of the battery 22 to be fitted and for the sealing material 40 to penetrate. There are no particular restrictions on the gap between the inner wall of the first recess 20 and the side surface of the battery 22, but for example, it should be in the range of 0.05 to 0.1 mm.

[0032] The second battery holder 12 is, for example, a box-shaped member having a bottom surface but no top surface, and the bottom surface is provided with a plurality of second recesses 30 that hold a plurality of batteries 22 such that adjacent batteries are spaced apart from each other. The shape of the second recesses 30 is, for example, a shape that follows the outer diameter of the battery 22. For a cylindrical battery to be housed, the shape of the second recesses 30 should be a circular shape that follows the circular outer diameter of the battery. If the battery to be housed is a rectangular prism, the shape of the second recesses 30 should be a rectangular shape that follows the rectangular outer diameter of the rectangular prism battery.

[0033] The shape of the second recess 30 is equivalent to the outer diameter shape of the battery 22. The gap between the inner wall of the second recess 30 and the side surface of the battery 22 does not need to be large enough to accommodate the other end of the battery 22, and there are no particular restrictions, but it can be in the range of 0.05 to 0.1 mm, for example.

[0034] In the method for manufacturing the battery pack according to this embodiment, the battery 22 is placed in the first recess 20 of the first battery holder 10 with the opening of the recess 20 facing upwards. Next, with the first battery holder 10 facing upwards, the current collector plate 36 is attached, and then the sheet material 42, 44 or release member 46 is attached. After that, with the first battery holder 10 facing downwards, the sealing material 40 is poured into the first battery holder 10 from the side where the battery 22 is inserted to form a sealing portion 28. If a release member 46 is used, the release member 46 is removed after the sealing material 40 has hardened.

[0035] The second battery holder 12 is positioned above the first battery holder 10 after a sealing portion 28 has been formed on the first battery holder 10, and the other end of the battery 22, which is on the upper side, is fitted into the second recess 30. In this way, both ends of the battery 22 are fitted into the first recess 20 and the second recess 30, and as a result, each battery 22 is fixed and held by the first recess 20 of the first battery holder 10 and the second recess 30 of the second battery holder 12, and each of the multiple batteries 22 is fixed and held in a state where it is spaced apart from the adjacent battery 22.

[0036] After combining the first battery holder 10 and the second battery holder 12, they are housed inside the casing 14, and the opening at the top is covered with the top plate 16.

[0037] The depths of the first recess 20 of the first battery holder 10 and the second recess 30 of the second battery holder 12 may be, for example, in the range of 5% to 20% of the height of the battery 22.

[0038] The shortest distance between adjacent batteries 22 within the battery pack 1 can be, for example, set to a range of 2% to 15% of the diameter of the battery 22.

[0039] The battery 22 housed in the battery pack 1 is, for example, a lithium-ion secondary battery, but is not limited to a lithium-ion secondary battery and can be any type of battery, as long as its shape is columnar, such as cylindrical or prismatic.

[0040] The materials that make up the first battery holder 10 and the second battery holder 12 are, for example, metal materials, resin materials, etc.

[0041] A material constituting the case 14 is, for example, a metal material, a resin material, or the like.

[0042] A material constituting the top plate 16 is, for example, a metal material, a resin material, or the like.

[0043] As the sealing material 40, for example, an epoxy adhesive having 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 (Room Temperature Vulcanizing) rubber or silicone RTV rubber may be used.

[0044] The sheet material 42 is not particularly limited as long as it is a sheet having high heat shrinkability, and examples thereof include a film formed of a resin such as polypropylene, polyethylene, or polyethylene terephthalate. The thickness of the sheet material 42 may be, for example, 10 to 250 µm.

[0045] The sheet material 44 is not particularly limited as long as it is a sheet having high heat shrinkability and a relatively large thickness, and examples thereof include a thick sheet material having high heat shrinkability such as foamed rubber or foamed resin, and a plate material of mica or resin. The thickness of the sheet material 44 may be, for example, 0.5 to 10 mm.

[0046] The release member 46 is not particularly limited as long as it has high releasability, and examples thereof include a member formed of a fluororesin, silicone rubber, or the like.

[0047] The sealing portion 33 provided at the connection between the first battery holder 10 and the second battery holder 12, the sealing portion 34 provided at the connection between the second battery holder 12 and the coolant inflow portion 18, and the sealing portion 35 provided at the connection between the second battery holder 12 and the coolant outflow portion 19 are not particularly limited as long as they can seal the respective portions, and for example, an O-ring, a packing, a liquid gasket, or the like can be used.

[0048] The cooling liquid 32 is not particularly limited as long as it is an insulating liquid capable of cooling the battery 22. For example, fluorine-based inert liquids such as insulating oil, transformer oil, silicone oil, and hydrofluoroether can be used.

[0049] The current collector plate 36 is not particularly limited as long as it can electrically connect between the batteries 22. For example, highly conductive metal materials such as copper, nickel, and aluminum alloy can be used.

[0050] The lid member 38 is not particularly limited as long as it can form a space between the outer surface of the current collector plate 36 and the inner surface of the lid member 38. For example, metal materials, resin materials and the like can be used.

[0051] 1: battery pack, 10: first battery holder, 12: second battery holder, 14: housing, 16: top plate, 18: cooling liquid inlet, 19: cooling liquid outlet, 20: first recess, 22: battery, 24: cavity, 26: through hole, 28, 33, 34, 35: sealing portion, 30: second recess, 32: cooling liquid, 36: current collector plate, 38: lid member, 40: sealing material, 42, 44: sheet material, 46: release member.

Claims

1. A battery pack for housing a plurality of columnar batteries, comprising: a first battery holder having a plurality of first recesses into which one end of each battery fits and which holds the plurality of batteries apart from adjacent batteries; and a second battery holder having a plurality of second recesses into which the other end of each battery fits, wherein at least one through hole is provided at the bottom of each first recess, a current collector plate for electrically connecting the plurality of batteries is positioned through the through hole, and the gap between the first recess and the batteries is sealed by a sealing portion, the sealing portion being in the same plane as or inside the same plane as the current collector plate.

2. The battery pack according to claim 1, wherein a sheet material covering the through hole is provided on the side of the first recess of the first battery holder opposite to the side where one end of the battery is held.

3. The battery pack according to claim 1 or 2, further comprising a cover member positioned on the side opposite to the side in which one end of the battery is held in the first recess of the first battery holder, so as to cover the through hole at a predetermined distance.

4. A method for manufacturing a battery pack that houses a plurality of columnar batteries, wherein the battery pack comprises: a first battery holder having a plurality of first recesses into which one end of the batteries fits and the plurality of batteries are held such that adjacent batteries are spaced apart; and a second battery holder having a plurality of second recesses into which the other end of the batteries fits, wherein at least one through hole is provided at the bottom of the first recess, and the method includes the step of holding one end of the batteries in the first recess, arranging a current collector plate for electrically connecting the plurality of batteries through the through hole, and then flowing a sealing material into the gap between the batteries and the first recess to form a sealing portion in the gap between the first recess and the batteries and sealing it, wherein the sealing portion is in the same plane as or inside the same plane as the current collector plate.

5. The method for manufacturing a battery pack according to claim 4, wherein a sheet material covering the through hole is provided on the side of the first recess of the first battery holder opposite to the side where one end of the battery is held.

6. The method for manufacturing a battery pack according to claim 4 or 5, further comprising a cover member positioned on the side opposite to the side in the first recess of the first battery holder where one end of the battery is held, so as to cover the through hole at a predetermined distance.

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