WO2023162438A1

WO2023162438A1 - Battery pack

Info

Publication number: WO2023162438A1
Application number: PCT/JP2022/046907
Authority: WO
Inventors: 喜幸坂内
Original assignee: 株式会社村田製作所
Priority date: 2022-02-22
Filing date: 2022-12-20
Publication date: 2023-08-31

Abstract

A battery pack according to one aspect of the present invention is provided with: a plurality of batteries; and a buried member that is buried in a gap among the plurality of batteries. The buried member internally contains a plurality of capsules. The capsules each have a first heat absorbing agent and a wall material that internally contains the first heat absorbing agent. The wall material is formed of a resin.

Description

battery pack

This technology relates to battery packs.

Due to the widespread use of electronic devices, batteries are being developed as power sources for such electronic devices. In this case, a battery pack including a plurality of batteries has been proposed in order to handle the plurality of batteries easily and safely.

Various studies have been conducted on technologies related to the configuration of battery packs. Specifically, a heat-absorbing member is in contact with the side surface of the battery unit, and the heat-absorbing member contains a heat-absorbing agent (liquid or gel-like fluid) inside the exterior film (see, for example, Patent Document 1). . A heat-absorbing substance is contained inside the exterior material, and the heat-absorbing substance is composed of a heat-storage gel in which heat-storage particles (microcapsules containing a latent heat storage agent) are dispersed (see, for example, Patent Document 2). .

WO 2010/098067 pamphlet Japanese Patent Application Laid-Open No. 2001-299801

However, in the invention described in Patent Document 1, when the exterior film melts due to abnormal heat generation of the battery, a large amount of the heat-absorbing agent leaks out at once. Therefore, the heat-absorbing agent cannot remain on the surface of the abnormally heated battery, and the heat-absorbing effect due to the sensible heat and latent heat of vaporization of the heat-absorbing agent may be reduced. In the invention described in Patent Document 2, it is not assumed that the heat storage gel leaks from the exterior material during use. Therefore, it is difficult to efficiently cool the abnormally heated battery. Therefore, it is desirable to provide a battery pack that can efficiently cool the abnormally heated battery.

A battery pack according to a first aspect of the present technology includes a plurality of batteries and an embedding member embedded in gaps between the plurality of batteries. The implant member contains a plurality of capsules. Each capsule has a first endothermic agent and a wall material enclosing the first endothermic agent. The wall material is made of resin.

A battery pack according to a second aspect of the present technology includes a plurality of batteries and an embedding member embedded in gaps between the plurality of batteries. The embedded member contains a heat-absorbing agent, and is configured such that the heat-absorbing agent gradually leaks to the outside along with the abnormal heat generation of the battery when the battery generates abnormal heat.

According to the battery pack according to the first aspect of the present technology, the plurality of capsules containing the heat-absorbing agent are used as the embedding member embedded in the gaps between the plurality of batteries, and the wall material of each capsule is made of resin. Therefore, when the battery generates abnormal heat, a large amount of the heat-absorbing agent does not leak at once, and the abnormally heated battery can be efficiently cooled.

According to the battery pack according to the second aspect of the present technology, the heat-absorbing agent is embedded in the embedded member embedded in the gap between the plurality of batteries, and when the batteries generate abnormal heat, the heat-absorbing agent Since a large amount of the heat-absorbing agent does not leak out at once, it is possible to efficiently cool the abnormally heated battery.

It should be noted that the effects of the present technology are not necessarily limited to the effects described here, and may be any of a series of effects related to the present technology described below.

FIG. 1 is a diagram illustrating a perspective configuration example of a battery pack according to an embodiment of the present technology. FIG. 2 is a diagram showing a perspective configuration example of a battery module housed in a battery pack. FIG. 3 is a view showing an example of the exploded perspective configuration of the battery module. FIG. 4A is a diagram showing a perspective configuration example of an embedding member. FIG. 4B is a diagram showing a cross-sectional configuration example of the embedding member. FIG. 5 is a diagram showing a perspective configuration example of a microcapsule. FIG. 6 is a diagram showing an example of particle size distribution of a plurality of microcapsules contained in the embedding member. FIG. 7 is a diagram showing a modified example of the batteries and the embedded member accommodated in the battery pack. FIG. 8 is a diagram showing a state in which the battery and the embedding member in FIG. 7 are overlaid.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this technique is demonstrated in detail with reference to drawings. The order of explanation is as follows.
1. Battery pack 1-1. Configuration 1-2. Effect 2. Modification 3. Applications of battery packs

<1. Battery pack>
First, a battery pack according to an embodiment of the present technology will be described.

The battery pack described here is a power supply with multiple batteries, and is applied to various applications such as electronic devices. The details of the application of the battery pack will be described later. Since the type of battery is not particularly limited, it may be a primary battery or a secondary battery. The type of secondary battery is not particularly limited, but specifically, it is a lithium ion secondary battery in which battery capacity is obtained by utilizing absorption and release of lithium ions. The number of batteries is not particularly limited and can be set arbitrarily. A case where the battery is a secondary battery (lithium ion secondary battery) will be described below. That is, the battery pack described below is a power supply that includes a plurality of secondary batteries.

<1-1. Overall configuration>
FIG. 1 shows a perspective configuration example of a battery pack 1 . FIG. 2 shows a perspective configuration example of the battery module 30 housed in the battery pack 1 . FIG. 3 shows an example of an exploded perspective configuration of the battery module 30. As shown in FIG.

For example, as shown in FIG. 1, the battery pack 1 includes an exterior case 10, battery modules 30 housed in the exterior case 10, and a control board (not shown). The control board is connected, for example, to the positive and negative terminals of the battery module 30, and detects the remaining capacity of the battery module 30, measures the current output from the battery module 30, and detects the presence or absence of overcurrent. It has a circuit that

The exterior case 10 is provided with an external terminal 20 connected to the control board. A battery module 30 is connected to the external terminal 20 via a control board. The battery pack 1 has a discharge mode in which the power output from the battery module 30 is supplied to the load via the external terminal 20 . Battery pack 1 may further have a charge mode in which power supplied from a power supply connected to external terminal 20 via external terminal 20 is stored in battery module 30 . When the battery 31 described below is a secondary battery, the control board switches between a discharge mode and a charge mode according to the type of the connected object connected to the external terminal 20 . When the battery 31, which will be described later, is a primary battery, the control board executes only the discharge mode.

The battery module 30 has a plurality of batteries 31 as shown in FIGS. 2 and 3, for example. The plurality of batteries 31 are electrically connected via

lead plates

34a, 34b, and 34c, as shown in FIGS. 2 and 3, for example. For example, when a plurality of batteries 31 that are a part of the plurality of batteries 31 are connected in series with each other, and the plurality of batteries 31 connected in series with each other are referred to as series units, the plurality of series units are connected in parallel with each other. In addition, the connection mode of the plurality of batteries 31 is not limited to the above.

Each battery 31 is a primary battery or a secondary battery. When each battery 31 is a secondary battery, the type of the secondary battery is not particularly limited, but specifically, it is a lithium ion secondary battery in which battery capacity is obtained by utilizing absorption and release of lithium ions. . A case where each battery 31 is a secondary battery (lithium ion secondary battery) will be described below. That is, the battery pack 1 described below is a power source that includes a plurality of secondary batteries. Each battery 31 is a cylindrical battery.

The battery module 30 further includes, for example, as shown in FIGS. 2 and 3, a battery holder 32 that supports the plurality of batteries 31, and an embedding member 33 that is embedded in the gaps between the plurality of batteries 31. . The battery holder 32 has a structure that supports a plurality of batteries 31 in layers with predetermined gaps therebetween.

FIG. 4(A) shows a perspective configuration example of the embedding member 33 . FIG. 4B shows a cross-sectional configuration example of the embedding member 33 . The embedded member 33 is in contact with the surface (peripheral surface) of the plurality of batteries 31 supported by the battery holder 32 . The embedded member 33 has a shape corresponding to the shape of the gaps between the batteries 31 supported by the battery holder 32 . Like the battery 31, the embedded member 33 has an elongated columnar shape. Here, it is assumed that four or more cylindrical batteries 31 are hierarchically supported by the battery holder 32 with predetermined gaps interposed therebetween. At this time, the embedded member 33 is in contact with the surfaces (peripheral surfaces) of the four cylindrical batteries 31 adjacent to each other, and has a shape corresponding to the shape of the gap between the four cylindrical batteries 31 adjacent to each other, for example. It's becoming For example, in the embedding member 33, the cross section in the direction perpendicular to the extending direction of the embedding member 33 has a substantially rhombic shape. Hereinafter, the extending direction of the embedding member 33 will be referred to as the vertical direction for convenience, and the direction perpendicular to the extending direction of the embedding member 33 will be referred to as the lateral direction for convenience.

The embedding member 33 contains a heat-absorbing agent, and is configured such that the heat-absorbing agent gradually leaks to the outside along with the abnormal heat generation of the battery 31 when the battery 31 generates abnormal heat. The embedding member 33 has, for example, a plurality of microcapsules 33b and a film 33a (exterior material) covering the plurality of microcapsules 33b, as shown in FIGS. 4A and 4B. .

For example, as shown in FIG. 5, the microcapsule 33b has a heat absorbing agent 33b1 and a wall material 33b2 containing the heat absorbing agent 33b1. The wall member 33b2 is made of resin. Each microcapsule 33b has a structure in which an endothermic agent 33b1 is sealed by a wall member 33b2. The particle size of each microcapsule 33b is 0.1 μm or more and 100 μm or less. When the gap between the plurality of batteries 31 is about 0.5 mm, the particle size of each microcapsule 33b is 100 μm or less, so that the embedded member 33 is arranged in the gap between the plurality of batteries 31 without gaps. Is possible. Here, if the particle size of the microcapsules 33b is less than 0.1 μm, the ratio of the wall material to the heat-absorbing agent increases, and the amount of heat absorption decreases, so there is a possibility that a sufficient effect cannot be obtained. Also, if the particle size of the microcapsules 33b is larger than 100 μm, it becomes difficult to dispose a sufficient amount of capsules in the gaps of the battery.

The plurality of microcapsules 33b contained in the embedding member 33 may contain, for example, multiple types of microcapsules 33b having at least two peaks in particle size distribution, as shown in FIG. At this time, among the plurality of microcapsules 33b contained in the embedding member 33, the plurality of microcapsules 33b included in group A having a relatively small particle size are mainly arranged at the corners of the embedding member 33 and the vicinity thereof. , the plurality of microcapsules 33b included in group B having a relatively large particle size are mainly arranged in the center of the embedding member 33 and its vicinity. In this case, it is possible to arrange the embedded member 33 even more tightly in the gaps between the plurality of batteries 31 . It should be noted that it is possible to dispose the endothermic agent without gaps even with only the microcapsules 33b included in group A having a relatively small particle size. However, if only the microcapsules 33b included in Group A are used, the ratio of the wall material to the heat-absorbing agent increases, and the amount of heat absorption decreases, so there is a possibility that a sufficient effect cannot be obtained. Therefore, it is more preferable to include a plurality of types of microcapsules 33b having at least two peaks in the particle size distribution.

The film 33a and the wall material 33b2 are made of a material with a heat-resistant temperature lower than the abnormal heat generation temperature of the battery 31 (for example, about 600°C). The wall material 33b2 is made of, for example, at least one of polyamide, polystyrene, polyethylene and polypropylene. The heat-resistant temperature of the film 33a is lower than the heat-resistant temperature of the wall material 33b2. The film 33a is made of, for example, at least one of polyethylene, polystyrene, polypropylene, and polycarbonate, and is made of a material whose heat resistance temperature is lower than that of the wall material 33b2. As a result, when the battery 31 generates abnormal heat, the film 33a melts first, and then the wall material 33b2 near the battery 31 melts. will come to The plurality of microcapsules 33b included in the embedding member 33 may include, for example, a plurality of types of capsules having mutually different heat resistance temperatures of the wall materials 33b2.

The endothermic agent 33b1 is configured to contain, for example, a liquid containing water or hydrogel. The endothermic agent 33b1 includes, for example, sodium polyacrylate, polyvinyl alcohol, polyhydroxyethyl methacrylate, or silicone hydrogel.

The gaps between the plurality of microcapsules 33b and the film 33a are, for example, voids. The embedding member 33 may have an endothermic agent that fills the gaps between the plurality of microcapsules 33b and the film 33a. At this time, the endothermic agent contains, for example, sodium polyacrylate, polyvinyl alcohol, polyhydroxyethyl methacrylate, or silicone hydrogel. This endothermic agent may be made of the same material as the endothermic agent 33b1.

<1-2. Effect>
Next, effects of the battery pack 1 will be described.

However, in the invention described in Patent Document 1, when the exterior film melts due to abnormal heat generation of the battery, a large amount of the heat-absorbing agent leaks out at once. Therefore, the heat-absorbing agent cannot remain on the surface of the abnormally heated battery, and the heat-absorbing effect due to the sensible heat and latent heat of vaporization of the heat-absorbing agent may be reduced. In the invention described in Patent Document 2, it is not assumed that the heat storage gel leaks from the exterior material during use. Therefore, it is difficult to efficiently cool the abnormally heated battery.

On the other hand, in the present embodiment, a plurality of microcapsules 33b containing a heat-absorbing agent 33b1 are used as the embedded member 33 embedded in the gaps between the plurality of batteries 31, and the wall material 33b2 of each microcapsule 33b is made of resin. formed. As a result, when the battery 31 generates abnormal heat, a large amount of the heat-absorbing agent 33b1 does not leak at once, and the abnormally heated battery 31 can be efficiently cooled.

Further, in the present embodiment, each microcapsule 33b has a structure in which the endothermic agent 33b1 is sealed by the wall material 33b2. As a result, when the battery 31 generates abnormal heat, a large amount of the heat-absorbing agent 33b1 does not leak at once, and the abnormally heated battery 31 can be efficiently cooled.

Also, in the present embodiment, the particle size of each microcapsule 33b is 0.1 μm or more and 100 μm or less. As a result, the embedded member 33 can be arranged in the gaps between the plurality of batteries 31 without gaps, so that the abnormally heated batteries 31 can be efficiently cooled.

Also, in the present embodiment, the plurality of microcapsules 33b contained in the embedding member 33 contain a plurality of types of capsules having at least two peaks in particle size distribution. As a result, for example, the plurality of microcapsules 33b included in the relatively small particle size group are arranged mainly at and near the corners of the embedding member 33, and the plurality of relatively large particle size groups included in the microcapsules 33b are arranged. By arranging the microcapsules 33b mainly at and near the center of the embedding member 33, it is possible to arrange the embedding member 33 in the gaps between the plurality of batteries 31 with even less gaps. As a result, it is possible to efficiently cool the abnormally heated battery 31 . It should be noted that it is possible to dispose the endothermic agent without gaps even with only the microcapsules 33b included in group A having a relatively small particle size. However, if only the microcapsules 33b included in Group A are used, the ratio of the wall material to the heat-absorbing agent increases, and the amount of heat absorption decreases, so there is a possibility that a sufficient effect cannot be obtained. Therefore, it is more preferable to include a plurality of types of microcapsules 33b having at least two peaks in the particle size distribution.

In the present embodiment, when the plurality of microcapsules 33b included in the embedding member 33 include a plurality of types of capsules having mutually different heat resistance temperatures of the wall material 33b2, the plurality of microcapsules included in the embedding member 33 The microcapsules 33b can be melted stepwise over time. Thereby, it is possible to cool the abnormally heated battery 31 for a long time.

Also, in the present embodiment, the heat-resistant temperature of the film 33a is lower than the heat-resistant temperature of the wall material 33b2. As a result, when the battery 31 generates abnormal heat, the film 33a melts first, and then the wall material 33b2 near the battery 31 melts. will come to As a result, it is possible to cool the abnormally heated battery 31 for a long time.

Further, in the present embodiment, when a heat absorbing agent is provided to fill the gaps between the plurality of microcapsules 33b and the film 33a, the cooling capacity of the filling member 33 is improved, so that the abnormally heated battery 31 can be reliably cooled. can be cooled to

<3. Variation>
Next, a modification of the battery pack 1 according to the above embodiment will be described.

(Modification A)
In the above embodiment, the battery 31 has a cylindrical shape, the embedded member 33 has an elongated columnar shape like the battery 31, and the cross section in the direction perpendicular to the extending direction of the embedded member 33 has a substantially diamond shape. It was. However, in the above embodiment, for example, as shown in FIGS. , a flat-shaped embedding member 36 may be used. FIG. 7 shows a modified example of the battery 35 and the embedded member 36 accommodated in the battery pack 1. As shown in FIG. FIG. 8 shows how the battery 35 and the embedding member 36 of FIG. 7 are overlaid.

The plurality of batteries 35 are electrically connected, for example, via predetermined lead plates. For example, when a plurality of batteries 35 that are part of the plurality of batteries 35 are connected in series with each other, and the plurality of batteries 35 connected in series with each other are referred to as a series unit, the plurality of series units are connected in parallel with each other. In addition, the connection mode of the plurality of batteries 35 is not limited to the above.

Each battery 35 is a primary battery or a secondary battery. When each battery 35 is a secondary battery, the type of the secondary battery is not particularly limited, but specifically, it is a lithium ion secondary battery in which battery capacity is obtained by utilizing absorption and release of lithium ions. .

The embedding member 36 is arranged between the two batteries 35 and is in contact with the surfaces of the two batteries 35 . The embedding member 36 contains a heat-absorbing agent, and is configured such that the heat-absorbing agent leaks to the outside when the battery 35 generates abnormal heat. Like the embedded member 33, the embedded member 36 contains a heat-absorbing agent. is configured to The embedding member 36 has, for example, a plurality of microcapsules 33b and a film 33a (exterior material) covering the plurality of microcapsules 33b.

Thus, even when the flat-shaped battery 35 is used instead of the cylindrical battery 31 and the flat-shaped embedding member 36 is used instead of the pillar-shaped embedding member 33, the above-described implementation is possible. As with the shape, heat-generating locations can be efficiently cooled.

(Modification B)
In the above embodiment and its modification, the embedding

members

33 and 36 are provided with a plurality of microcapsules 33b. However, in the above embodiment and its modification, instead of the plurality of microcapsules 33b, a heat-absorbing agent is included, and when the

batteries

31 and 35 generate abnormal heat, the heat-absorbing agent 33b1 causes the battery 31 to generate abnormal heat. It may be configured to gradually leak to the outside along with. Even in this case, it is possible to efficiently cool the heat-generating portion similarly to the above-described embodiment and its modification.

<3. Application of battery pack>
The battery pack 1 is used in machines, devices, instruments, devices, and systems (aggregates of multiple devices, etc.) that can use the battery pack 1 as a power source for driving and a power storage source for power storage. If there is, it is not particularly limited.

The battery pack 1 used as a power source may be a main power source or an auxiliary power source. A main power source is a power source that is preferentially used regardless of the presence or absence of other power sources. The auxiliary power supply may be, for example, a power supply that is used in place of the main power supply, or may be a power supply that is switched from the main power supply as needed. When using a battery pack as an auxiliary power supply, the main power supply is not limited to the battery pack.

An example of the usage of the battery pack 1 is as follows. Electronic devices (including portable electronic devices) such as video cameras, digital still cameras, mobile phones, notebook personal computers, cordless phones, headphone stereos, portable radios, portable televisions, and portable information terminals. It is a portable household appliance such as an electric shaver. Backup power and storage devices such as memory cards. Power tools such as power drills and power saws. Medical electronic devices such as pacemakers and hearing aids. It is an electric vehicle such as an electric vehicle (including a hybrid vehicle). It is an electric power storage system such as a home battery system that stores electric power in preparation for emergencies. Of course, the battery pack may be used for purposes other than those described above.

Although the present technology has been described above while citing one embodiment, the present technology is not limited to the aspect described in the above-described one embodiment, and various modifications of the present technology are possible.

Specifically, the case where the battery structure of the secondary battery is cylindrical has been described, but the battery structure of the secondary battery applied to the battery pack of the present technology is not particularly limited. Specifically, the battery structure of the secondary battery may be a laminate film type, a square type, a coin type, or the like.

Also, although the case where the secondary battery has a wound structure has been described, the structure of the secondary battery is not particularly limited. Specifically, the secondary battery may have other structures such as a laminated structure.

Also, although lithium was used as the electrode reactant of the secondary battery, the type of the electrode reactant is not particularly limited. Specifically, the electrode reactant may be another group 1 element in the long period periodic table such as sodium and potassium, a group 2 element in the long period periodic table such as magnesium and calcium, or aluminum Other light metals such as

Since the effects described in this specification are merely examples, the effects of the present technology are not limited to the effects described in this specification. Accordingly, other advantages may be obtained with respect to the present technology.

In addition, this technique can also take the following structures.
<1>
a plurality of batteries;
and an embedding member embedded in the gaps between the plurality of batteries,
The embedding member encloses a plurality of capsules,
each of the capsules has a first endothermic agent and a wall material enclosing the first endothermic agent;
In the battery pack, the wall material is made of resin.
<2>
The battery pack according to claim 1, wherein each capsule has a structure in which the first endothermic agent is sealed by the wall material.
<3>
The battery pack according to <1> or <2>, wherein the wall material is made of at least one material selected from polyamide, polystyrene, polyethylene, and polypropylene.
<4>
The battery pack according to any one of <1> to <3>, wherein each capsule has a particle size of 0.1 μm or more and 100 μm or less.
<5>
The battery pack according to <4>, wherein the plurality of capsules include a plurality of types of capsules having at least two peaks in particle size distribution.
<6>
The battery pack according to any one of <1> to <5>, wherein the plurality of capsules include a plurality of types of capsules in which the wall materials have different heat resistance temperatures.
<7>
The battery pack according to any one of <1> to <6>, wherein the first endothermic agent includes liquid containing water or hydrogel.
<8>
The battery pack according to any one of <1> to <6>, wherein the first endothermic agent includes sodium polyacrylate, polyvinyl alcohol, polyhydroxyethyl methacrylate, or silicone hydrogel.
<9>
The battery pack according to any one of <1> to <8>, wherein the embedding member further includes an exterior material enclosing the plurality of capsules.
<10>
The battery pack according to <9>, wherein the heat-resistant temperature of the exterior material is lower than the heat-resistant temperature of the wall material.
<11>
The battery pack according to <10>, wherein the exterior material is made of at least one material selected from polyethylene, polystyrene, polypropylene, and polycarbonate, and is made of a material having a heat resistance temperature lower than that of the wall material.
<12>
The battery pack according to any one of <9> to <11>, wherein the embedding member includes a second endothermic agent that fills a gap between the plurality of capsules and the exterior material.
<13>
The battery pack according to <12>, wherein the second endothermic agent includes sodium polyacrylate, polyvinyl alcohol, polyhydroxyethyl methacrylate, or silicone hydrogel.
<14>
The embedding member further has an exterior material enclosing the plurality of capsules,
The first endothermic agent contains an acidic liquid,
The battery pack according to any one of <1> to <6>, wherein the second endothermic agent contains powdered sodium bicarbonate.
<15>
further comprising a battery holder that supports the plurality of batteries in a layered manner with predetermined gaps therebetween;
The battery pack according to any one of <1> to <14>, wherein the embedded member is in contact with the peripheral surface of the battery.
<16>
The battery pack has four or more cylindrical batteries as the plurality of batteries,
The battery pack according to <15>, wherein the embedded member is in contact with the peripheral surfaces of the four cylindrical batteries that are adjacent to each other.
<17>
The battery pack according to <16>, wherein the embedded member has a shape corresponding to a shape of a gap between the four cylindrical batteries adjacent to each other.
<18>
a plurality of batteries;
and an embedding member to be embedded in the gaps between the plurality of batteries,
The embedded member contains a heat-absorbing agent, and is configured such that when the battery generates abnormal heat, the heat-absorbing agent gradually leaks to the outside along with the abnormal heat generation of the battery. .

Claims

a plurality of batteries;
and an embedding member embedded in the gaps between the plurality of batteries,
The embedding member encloses a plurality of capsules,
each of the capsules has a first endothermic agent and a wall material enclosing the first endothermic agent;
In the battery pack, the wall material is made of resin.
The battery pack according to claim 1, wherein each capsule has a structure in which the first endothermic agent is sealed by the wall material.
3. The battery pack according to claim 1, wherein the wall material is made of at least one material selected from polyamide, polystyrene, polyethylene, and polypropylene.
The battery pack according to any one of claims 1 to 3, wherein each capsule has a particle size of 0.1 µm or more and 100 µm or less.
The battery pack according to claim 4, wherein the plurality of capsules include a plurality of types of capsules having at least two peaks in particle size distribution.
The battery pack according to any one of claims 1 to 5, wherein the plurality of capsules include a plurality of types of capsules in which the wall materials have different heat resistance temperatures.
The battery pack according to any one of claims 1 to 6, wherein the first endothermic agent includes liquid containing water or hydrogel.
The battery pack according to any one of claims 1 to 6, wherein the first endothermic agent includes sodium polyacrylate, polyvinyl alcohol, polyhydroxyethyl methacrylate, or silicone hydrogel.
The battery pack according to any one of claims 1 to 8, wherein the embedded member further includes an exterior material that encloses the plurality of capsules.
The battery pack according to claim 9, wherein the heat-resistant temperature of the exterior material is lower than the heat-resistant temperature of the wall material.
11. The battery pack according to claim 10, wherein the exterior material is made of at least one material selected from polyethylene, polystyrene, polypropylene, and polycarbonate, and is made of a material whose heat resistance temperature is lower than that of the wall material.
The battery pack according to any one of claims 9 to 11, wherein the embedding member has a second heat-absorbing agent that fills gaps between the plurality of capsules and the exterior material.
The battery pack according to claim 12, wherein the second endothermic agent includes sodium polyacrylate, polyvinyl alcohol, polyhydroxyethyl methacrylate, or silicone hydrogel.
The embedding member further has an exterior material enclosing the plurality of capsules,
The first endothermic agent contains an acidic liquid,
The battery pack according to any one of claims 1 to 6, wherein the second endothermic agent contains powdered sodium bicarbonate.
further comprising a battery holder that supports the plurality of batteries in a layered manner with predetermined gaps therebetween;
The battery pack according to any one of claims 1 to 14, wherein the embedded member is in contact with the peripheral surface of the battery.
The battery pack has four or more cylindrical batteries as the plurality of batteries,
The battery pack according to claim 15, wherein the embedded member is in contact with the peripheral surfaces of the four cylindrical batteries that are adjacent to each other.
17. The battery pack according to claim 16, wherein the embedded member has a shape corresponding to the shape of the gap between the four cylindrical batteries adjacent to each other.
a plurality of batteries;
and an embedding member embedded in the gaps between the plurality of batteries,
The embedded member contains a heat-absorbing agent, and is configured such that when the battery generates abnormal heat, the heat-absorbing agent gradually leaks to the outside along with the abnormal heat generation of the battery. .