Battery pack and method of producing battery pack

Abstract

Provided is a battery pack accommodating a plurality of columnar batteries, wherein a collector plate for electrically connecting the batteries to one another is disposed, and then an exhaust path is secured and components are sealed from one another. A battery pack (1) is provided with: a first battery holder (10) provided with a plurality of first recesses (20) into each of which one end of a battery (22) is fitted and which hold a plurality of batteries so that adjacent batteries are separated from one another; and a second battery holder (12) provided with a plurality of second recesses (30) into which the other ends of the batteries (22) are fitted. The first recesses (20) are each constituted of, in order from the side where the batteries (22) are held, a first section (23) having a shape larger than the outer diameter shape of the battery (22) and a second section (24) having a shape equivalent to the outer diameter shape of the battery (22). At least one through hole (26) is provided to the bottom of the first recess (23). A collector plate (36) for electrically connecting the plurality of batteries (22) through the through holes (26) is arranged. Gaps between the first recesses (20) and the batteries (22) are each sealed by a sealing portion (28).

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 relates to a battery pack accommodating 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 such as columnar shapes including 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 interior of the pack is filled with an insulating cooling liquid. Immersion cooling includes a full-immersion type in which the entire interior of the pack is filled with cooling liquid, and a partial-immersion type in which the cooling liquid can be held at required locations within the pack. The partial-immersion type has the advantage of reducing the amount of cooling liquid and reducing the weight of the battery pack, but on the other hand, 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 placed in a battery holder that holds the batteries, and sealing is performed 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 of a battery is sealed by inserting the battery after filling an adhesive to a predetermined height in the battery holder (see FIG. 5 of Patent Document 1), and the other end is sealed by inserting a waterproof adhesive to a predetermined height in a battery case and then putting the assembled battery and battery holder into the case to seal between the battery holder and the battery case (see FIG. 9 of Patent Document 1), thereby forming an independent space in which cooling liquid can flow inside the cell holder (see FIG. 1 of Patent Document 1).

[0005] Japanese National Publication of International Patent Application No. 2023-528041

[0006] However, in the configuration of Patent Document 1, it is not possible to place a current collector plate for electrical connection between the batteries on one end of the battery that is initially sealed and on the battery holder side, and the exhaust path for releasing pressure from inside the battery when the internal pressure of the battery rises is filled with adhesive, creating design constraints on current collection and exhaust.

[0007] The purpose of this disclosure is to provide a battery pack containing multiple columnar batteries, wherein current collector plates for electrical connection between the batteries are arranged, an exhaust path is secured, and the components are sealed together, and a method for manufacturing the battery pack is provided.

[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 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 of the first recesses is composed of a first portion having a shape larger than the outer diameter of the battery and a second portion having a shape equivalent to the outer diameter of the battery, in order from the side into which the battery is held; at least one through hole is provided at the bottom of the 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.

[0009] This disclosure relates to a method for manufacturing a battery pack for housing a plurality of columnar batteries, the battery pack comprising: 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 of the first recesses is composed of a first portion having a shape larger than the outer diameter of the battery and a second portion having a shape equivalent to the outer diameter of the battery, in order from the side in which the battery is held, and at least one through hole is provided at the bottom of the first recess, the method for manufacturing a battery pack comprising the steps of holding one end of the battery 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 battery and the first portion to form a sealing portion in the gap between the first recess and the battery and seal it.

[0010] This disclosure provides a battery pack containing multiple columnar batteries, wherein current collector plates for electrical connection between the batteries are arranged, an exhaust path is secured, and the components are sealed together, and a method for manufacturing the battery pack is available.

[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 first battery holder in a battery pack according to the embodiment of this disclosure. This is a schematic diagram showing an example of a sealing structure and its manufacturing method in a battery pack according to the embodiment of this disclosure. This is a schematic diagram showing another example of a sealing structure and its manufacturing method in a battery pack according to the embodiment of this disclosure. This is a schematic diagram showing another example of a sealing structure and its manufacturing method 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 2 is a schematic diagram showing an example of a first battery holder in the battery pack according to this embodiment. Figure 1 is a diagram showing the battery pack according to this embodiment from the side, with the interior 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] As shown in Figure 2, 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. At least one of the first recesses 20 is composed of a first portion 23 which is larger in shape than the outer diameter of the battery 22 and a second portion 24 which is the same shape as the outer diameter of the battery 22, in order from the side in which the battery 22 is held, and at least one through hole 26 is provided at the bottom of the first recess 20. Adjacent first recesses 20 may be connected by the first portion 23. There are no particular restrictions on the arrangement position or number of 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 batteries 22 are fitted into the first recess 20 and the second recess 30, and 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 batteries 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 27 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 3 to 5 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 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 the multiple batteries 22 is placed through the through hole 26. Then, a sealing material 40 is poured in and fixed through the gap between the battery 22 and the first portion 23 of the first recess 20, forming a sealing portion 28 in the gap between the first recess 20 and the battery 22 to seal it.

[0027] In the method for manufacturing the battery pack according to this embodiment, the battery 22 is placed in the first battery holder 10 and the current collector plate 36 is attached. Next, 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 inserted, applied, and fixed to seal the space between the battery 22 and the first battery holder 10 after the current collector plate 36 has been assembled. The first recess 20 in the first battery holder 10 into which the battery 22 is fitted is composed of two stages, for example, a first portion 23 with a diameter larger than the diameter of the battery 22 and a second portion 24 with a diameter equal to the diameter of the battery 22. When an appropriate amount of sealing material 40 is poured from the first portion 23 into the area surrounded by three cylindrical cells, the sealing material 40 spreads out on the stepped surface of the first portion 23 and penetrates into the gap between the inner wall of the first recess 20 and the side of the battery 22. This allows for the formation of a sealing portion 28, thereby sealing the space between the inner wall of the first recess 20 of the first battery holder 10 and the side surface of the battery 22.

[0028] If the sealing material 40 has low viscosity, the applied sealing material 40 may flow out of the through hole 26 of the first battery holder 10. In that case, as shown in Figure 3, a lid member 38 may be provided on the side opposite to the side where one end of the battery 22 is held in the first recess 20 of the first battery holder 10, 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. This allows the sealing material 40 to accumulate in the space between the outer surface of the current collector plate 36 and the inner surface of the lid member 38, even if it flows out of the through hole 26 of the first battery holder 10. In this case, if the battery 22 has an exhaust valve on the side with the lid member 38 (i.e., one end side) to release pressure from inside the battery when the internal pressure of the battery rises, exhaust may become difficult in the sealing portion 28. Therefore, it is desirable to provide the exhaust valve of the battery 22 at the other end, which is opposite to the cover member 38.

[0029] The shape of the first recess 20 is, for example, a shape that conforms to the outer diameter of the battery 22. In the example in Figure 2, the shape of the first recess 20 is circular, conforming to the circular outer diameter of the cylindrical battery that is housed. If the battery to be housed is rectangular, the shape of the first recess 20 should be rectangular, conforming to the rectangular outer diameter of the rectangular battery.

[0030] The shape of the first portion 23 in the first recess 20 is larger than the outer diameter of the battery 22. The gap between the inner wall of the first portion 23 and the side surface of the battery 22 only needs to be large enough for the sealing material 40 to flow in, and there are no particular restrictions, but for example it should be in the range of 0.3 to 1 mm. The second portion 24 in the first recess 20 has a shape equivalent to the outer diameter of the battery 22. The gap between the inner wall of the second portion 24 and the side surface of the battery 22 only needs to be large enough to fit one end of the battery 22 and allow the sealing material 40 to penetrate. There are no particular restrictions on the gap between the inner wall of the second portion 24 and the side surface of the battery 22, but for example it should be in the range of 0.05 to 0.1 mm. The gap between the inner wall of the first portion 23 and the side surface of the battery 22 should be, for example, about 5 to 10 times larger than the gap between the inner wall of the second portion 24 and the side surface of the battery 22.

[0031] The steps of the first portion 23 and the second portion 24 in the first recess 20 do not necessarily have to be at a right angle. The first recess 20 may have a tapered shape in which the shape of the bottom portion (second portion 24) is the same as the outer diameter of the battery 22, and the diameter increases from the bottom portion towards the opening (first portion 23) into which the battery 22 fits, or conversely, the diameter narrows from the opening (first portion 23) towards the bottom portion (second portion 24). This has the advantage that multiple batteries 22 can be easily inserted into the first battery holder 10.

[0032] The taper angle in this tapered shape should be, for example, in the range of 90 degrees to 135 degrees. If this taper angle is less than 90 degrees, it may not be possible to securely hold the battery 22. If this taper angle exceeds 135 degrees, it may become difficult to fit the battery 22 into the first recess 20.

[0033] As shown in Figure 4, a sealing member 42 such as an O-ring may be fitted to the outer edge of the bottom surface of one end of the battery 22. The sealing member 42 can seal the gap between the side surface of one end of the battery 22 and the second portion 24 of the first recess 20. By filling the gap between the side surface of the battery 22 and the second portion 24 of the first battery holder 10, it is possible to suppress the sealing material 40 from flowing out of the through hole 26 of the first battery holder 10, even when a low-viscosity sealing material 40 is used. As shown in Figure 4, even when a current collector plate is welded to the shoulder of the bottom surface of the battery 22, it is possible to suppress the sealing material 40 from flowing out of the through hole 26 of the first battery holder 10. In addition, it is possible to secure an exhaust space when the battery 22 has an exhaust valve on one end side.

[0034] If a current collector plate is not welded to the shoulder of the bottom surface of the battery 22, a sealing member 44, such as a flat cylindrical member, may be placed between the bottom surface of one end of the battery 22 and the bottom surface of the second portion 24, for example, as shown in Figure 5. The sealing member 44 can seal the gap between the bottom surface of one end of the battery 22 and the second portion 24 of the first recess 20. By filling the gap between the bottom surface of the battery 22 and the second portion 24 of the first battery holder 10, it is possible to suppress the sealing material 40 from flowing out of the through hole 26 of the first battery holder 10, even when a low-viscosity sealing material 40 is used. In addition, it is possible to secure an exhaust space when the battery 22 has an exhaust valve on one end side.

[0035] 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.

[0036] 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.

[0037] 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, with the first battery holder 10 facing downwards, the sealing material 40 is poured into the battery holder 10 from the side where the battery 22 is inserted to form a sealing portion 28.

[0038] In this case, after attaching the current collector plate 36, an insulating material such as a resin or mica plate, an inorganic fiber nonwoven fabric, or a foamed resin sheet is placed on top of the current collector plate 36 and the device is turned upside down so that the first battery holder 10 is on the bottom. This prevents the current collector plate 36 from lifting up when turned upside down and prevents the current collector plate 36 from coming into contact with surrounding objects such as the surface on which the first battery holder 10 is placed, thereby preventing an external short circuit.

[0039] 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.

[0040] The second recess 30 may also have a tapered shape similar to that of the first recess 20. In this case, the taper angle of the second recess 30 may be within the same range as that of the first recess 20.

[0041] 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.

[0042] The depth of the first recess (20) of the first battery holder (10) and the depth of the second recess (30) of the second battery holder (12) may each be, for example, in a range of 5% or more and 20% or less relative to the height of the battery (22).

[0043] The shortest distance between adjacent batteries (22) in the battery pack (1) may be, for example, in a range of 2% or more and 15% or less of the diameter of the battery (22).

[0044] 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 may be any type of battery, as long as it has a columnar shape such as a cylindrical shape or a prismatic shape.

[0045] The materials constituting the first battery holder (10) and the second battery holder (12) are, for example, metal materials, resin materials, and the like.

[0046] The material constituting the housing (14) is, for example, a metal material, a resin material, or the like.

[0047] The material constituting the top plate (16) is, for example, a metal material, a resin material, or the like.

[0048] As the sealing material (40), for example, a methanol-resistant epoxy adhesive, an epoxy-modified silicone adhesive, a silicone-based adhesive, a fluorine-based adhesive, or an elastic adhesive such as butyl rubber-based urethane RTV (Room Temperature Vulcanizing) rubber, silicone RTV rubber, or the like may be used.

[0049] The sealing member (42) is not particularly limited as long as it can seal the gap between the side surface of one end of the battery (22) and the second portion (24) of the first recess (20), and examples thereof include an O-ring made of nitrile rubber, silicone rubber, fluorine rubber, or the like, an ultraviolet curable resin, and the like.

[0050] The sealing member (44) is not particularly limited as long as it can seal the gap between the bottom surface of one end of the battery (22) and the second portion (24) of the first recess (20), and examples thereof include a flat cylindrical member made of nitrile rubber, silicone rubber, fluorine rubber, or the like, a liquid gasket, and the like.

[0051] 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 inlet 18, and the sealing portion 35 provided at the connection between the second battery holder 12 and the coolant outlet 19 can be any material capable of sealing each of these sections, and there are no particular restrictions. For example, O-rings, packings, liquid gaskets, etc., can be used.

[0052] The coolant 32 can be any insulating liquid capable of cooling the battery 22, and is not particularly limited. For example, insulating oil, transformer oil, silicone oil, hydrofluoric acid ether, or other fluorine-based inert liquids can be used.

[0053] The current collector plate 36 can be anything that can electrically connect the batteries 22. There are no particular restrictions, but for example, highly conductive metal materials such as copper, nickel, or aluminum alloys can be used.

[0054] The cover member 38 can be any material that can form a space between the outer surface of the current collector plate 36 and the inner surface of the cover member 38. There are no particular restrictions, but for example, metal materials, resin materials, etc., can be used.

[0055] 1 Battery pack, 10 First battery holder, 12 Second battery holder, 14 Housing, 16 Top plate, 18 Coolant inlet, 19 Coolant outlet, 20 First recess, 22 Battery, 23 First part, 24 Second part, 26 Through hole, 27 Cavity, 28, 33, 34, 35 Sealing part, 30 Second recess, 32 Coolant, 36 Current collector plate, 38 Cover member, 40 Sealing material, 42, 44 Sealing members.

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 such that adjacent batteries are spaced apart; and a second battery holder having a plurality of second recesses into which the other end of each battery fits, wherein at least one of the first recesses is composed of a first portion having a shape larger than the outer diameter of the battery and a second portion having a shape equivalent to the outer diameter of the battery, in order from the side in which the battery is held; at least one through hole is provided at the bottom of the first recess, and 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 battery is sealed by a sealing portion.

2. The battery pack according to claim 1, 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.

3. The battery pack according to claim 1 or 2, further comprising a sealing member for sealing the gap between the side or bottom surface of one end of the battery and the second portion.

4. A method for manufacturing a battery pack for housing a plurality of columnar batteries, the battery pack comprising: 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 of the first recesses is composed of, in order from the side in which the battery is held, a first portion having a shape larger than the outer diameter of the battery and a second portion having a shape equivalent to the outer diameter of the battery, and at least one through hole is provided at the bottom of the first recess, and the method for manufacturing a battery pack comprising the steps of holding one end of the battery 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 battery and the first portion to form a sealing portion in the gap between the first recess and the battery and seal it.

5. The method for manufacturing a battery pack according to claim 4, further comprising a lid 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.

6. The method for manufacturing a battery pack according to claim 4 or 5, further comprising a sealing member for sealing the gap between the side or bottom surface of one end of the battery and the second portion.

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