Battery pack, power tool, and electric vehicle

Abstract

An effectively cooled temperature-increased battery. A battery pack has an outer case, a battery, a battery holder, and a heat absorbing portion. The heat absorbing portion is configured to absorb heat by phase change. The battery holder has a first battery holder and a second battery holder. The first battery holder holds an electrode portion of the battery. The second battery holder surrounds a main body portion of the battery. The second battery holder has a pool portion. The heat absorbing portion is housed in the pool portion.

Description

Technical Field

[0001] This invention relates to battery packs, power tools, and electric vehicles. Background Technology

[0002] Previously, techniques for cooling overheated batteries have been proposed. For example, Patent Document 1 describes a technique in which a heat storage material container, including a heat storage material, is housed together with the battery within a battery pack, thereby allowing the heat storage material within the heat storage material container to absorb the heat generated by the battery.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2002-291670 Summary of the Invention

[0006] The technical problem that the invention aims to solve

[0007] In the technology described in Patent Document 1, the heat storage material container needs to be housed inside the battery pack, which reduces the volumetric energy density of the battery pack. Furthermore, housing the heat storage material container inside the battery pack results in a larger battery pack and increased weight.

[0008] Therefore, one of the objectives of this invention is to provide a battery pack, power tool, and electric vehicle that can effectively cool a battery with rising temperature without causing a decrease in the volumetric energy density of the battery pack.

[0009] Technical solutions for solving technical problems

[0010] To solve the above-mentioned technical problems, the present invention provides a battery pack having:

[0011] External housing;

[0012] Battery;

[0013] Battery holder; and

[0014] heat absorption section,

[0015] The heat-absorbing section is configured to absorb heat through a phase change.

[0016] The battery holder has a first battery holder and a second battery holder. The first battery holder holds the electrode portion of the battery, and the second battery holder surrounds the main body portion of the battery.

[0017] The second battery holder has a battery compartment.

[0018] The heat-absorbing part is housed in the pool section.

[0019] Invention Effects

[0020] According to at least one embodiment of the present invention, batteries with elevated temperatures can be effectively cooled without causing a decrease in the volumetric energy density of the battery pack. It should be noted that the content of the present invention should not be construed as limited to the effects illustrated in this specification. Attached Figure Description

[0021] Figure 1 This is a diagram showing the appearance of a battery pack according to one embodiment.

[0022] Figure 2 This is an exploded perspective view of a battery cell according to one embodiment.

[0023] Figure 3 A and Figure 3 Figure B is a diagram used to illustrate an intermediate cage according to one embodiment.

[0024] Figure 4 This is a diagram used to illustrate the pool section in one embodiment.

[0025] Figure 5 This is a diagram used to illustrate the heat-absorbing part according to one embodiment.

[0026] Figure 6 This is a diagram used to illustrate the heat-absorbing part according to one embodiment.

[0027] Figure 7 This is a diagram used to illustrate the heat-absorbing part according to one embodiment.

[0028] Figure 8 This is a diagram used to illustrate the heat-absorbing part according to one embodiment.

[0029] Figure 9 This is a diagram illustrating an elastic component according to one embodiment.

[0030] Figure 10 The diagram shows a state in which an elastic member is installed on a battery according to one embodiment.

[0031] Figure 11 The diagram shows a state in which an elastic member is installed on a battery according to one embodiment.

[0032] Figure 12 A and Figure 12 Figure B is a diagram used to illustrate the function of the elastic member in one embodiment.

[0033] Figure 13 This is a diagram used to illustrate a variation.

[0034] Figure 14 This is a diagram used to illustrate a variation.

[0035] Figure 15 A~ Figure 15 D is a diagram used to illustrate a variation.

[0036] Figure 16 This is a diagram used to illustrate a variation.

[0037] Figure 17 This is a diagram used to illustrate an application example.

[0038] Figure 18 This is a diagram used to illustrate an application example. Detailed Implementation

[0039] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the descriptions will be presented in the following order.

[0040] <One Implementation Method>

[0041] <Variation Example>

[0042] <Application Examples>

[0043] The embodiments described below are suitable specific examples of the present invention, and the content of the present invention is not limited to these embodiments.

[0044] It should be noted that the components shown in the claims are not specific to the components of the embodiments. In particular, descriptions of the dimensions, materials, shapes, relative arrangements, and orientations (up, down, left, right, etc.) of the constituent components described in the embodiments, unless intended to be particularly limiting, are not intended to limit the scope of the invention to these descriptions, but are merely illustrative examples. It should be noted that the size and positional relationships of the components shown in the figures are sometimes exaggerated for clarity. In addition, to prevent the illustrations from becoming too complex, sometimes only a portion of the reference numerals or a simplified portion of the illustrations are shown. Furthermore, in the following description, the same names and symbols denote the same or homogeneous components, and repeated descriptions are appropriately omitted. Furthermore, the elements constituting the present invention can be composed of multiple elements made up of the same components, or one component can serve as multiple elements; conversely, multiple components can share the function of one component.

[0045] <One Implementation Method>

[0046] [Battery Pack]

[0047] (Example of appearance)

[0048] Figure 1This is a diagram showing the appearance of a battery pack (battery pack 1) according to one embodiment. The battery pack 1 has a generally box-shaped outer casing 10. The outer casing 10 is formed of resin, for example. The outer casing 10 has a cover-shaped upper outer casing 10A that is generally rectangular when viewed from above, and a shell-shaped lower outer casing 10B with an open upper surface. The upper outer casing 10A and the lower outer casing 10B are integrated, for example, by fastening with six fastening screws. The positive output terminal and the negative output terminal (not shown) are led out to the outside of the outer casing 10. Such positive output terminals and negative output terminals are connected to the load of the battery pack 1. It should be noted that when charging the battery pack 1, the positive output terminals and negative output terminals are used as charging terminals.

[0049] (Battery unit)

[0050] The battery unit is housed within the aforementioned outer casing 10. Figure 2 This is an exploded perspective view of a battery cell (battery cell 20) according to one embodiment. The battery cell 20 has a battery 21 and a battery holder 22 for housing and holding the battery 21. The battery holder 22 has a top holder 23, a bottom holder 24, and a middle holder 25.

[0051] Battery 21 has one or more individual cells. For example, battery 21 has a cylindrical lithium-ion secondary battery cell 21A with electrode portions 21B at both ends. In this embodiment, battery 21 has 28 lithium-ion secondary battery cells 21A, but the number and arrangement of lithium-ion secondary battery cells 21A can be appropriately changed. Each lithium-ion secondary battery cell 21A has a positive terminal as an electrode portion 21B at one end and a negative terminal as an electrode portion 21B at the other end. In the following description, the positive terminal or the negative terminal will be appropriately referred to as electrode portion 21B.

[0052] For example, through Figure 2The virtual plane PL shown divides the battery 21 into 14 lithium-ion secondary battery cells 21A in each group. In one group of 14 lithium-ion secondary battery cells 21A, the positive terminals of the two cells at the very end (one end side) face upwards, for example, and the negative terminals face downwards. The positive terminals of the two adjacent lithium-ion secondary battery cells 21A face downwards, for example, and the negative terminals face upwards. The lithium-ion secondary battery cells 21A are arranged in this alternating polarity direction. Similarly, in the other group of 14 lithium-ion secondary battery cells 21A, the positive terminals of the two cells at the very end (one end side) face downwards, for example, and the negative terminals face upwards. The positive terminals of the two adjacent lithium-ion secondary battery cells 21A face upwards, for example, and the negative terminals face downwards. The lithium-ion secondary battery cells 21A are arranged in this alternating polarity direction.

[0053] Furthermore, in this embodiment, an elastic member (an example of a blocking member) is provided to surround the electrode portion 21B of the lithium-ion secondary battery cell 21A. For example, an annular elastic member 21C is provided to surround the vicinity of the electrode portion 21B located on the top retainer 23 side of the lithium-ion secondary battery cell 21A, and an annular elastic member 21D is provided to surround the vicinity of the electrode portion 21B on the bottom retainer 24 side of the lithium-ion secondary battery cell 21A. In this embodiment, elastic member 21C and elastic member 21D correspond to an example of the first elastic member.

[0054] The battery holder 22 is made of resin, for example. The battery holder 22 holds the battery 21 in a designated position and ensures insulation between the lithium-ion secondary battery cells 21A. The intermediate holder 25 of the battery holder 22 is configured to be sandwiched between the top holder 23 and the bottom holder 24. It should be noted that the terms "top," "bottom," and "intermediate" are used for ease of explanation; when using the battery pack 1, the top holder 23 does not necessarily need to be positioned above the bottom holder 24.

[0055] The top retainer 23 has cylindrical retaining portions 23A corresponding to the number of lithium-ion secondary battery cells 21A. In this embodiment, each retaining portion 23A is provided independently. The electrode portion 21B on one side is held by the retaining portion 23A. In addition, a hole portion 23B is provided on the end face of the retaining portion 23A. A metal contact (not shown) is mounted on the top retainer 23 from the side opposite to the retaining portion 23A. The contact is welded to the electrode portion 21B of the lithium-ion secondary battery cell 21A exposed from the hole portion 23B. For example, a contact is welded to four adjacent lithium-ion secondary battery cells 21A, and a contact is mounted on the two lithium-ion secondary battery cells 21A located at the very end. The contact mounted on one of the two lithium-ion secondary battery cells 21A located at the very end is connected to the positive output terminal, and the contact mounted on the other of the two lithium-ion secondary battery cells 21A located at the very end is connected to the negative output terminal.

[0056] The bottom retainer 24 has cylindrical retaining portions 24A corresponding to the number of lithium-ion secondary battery cells 21A. In this embodiment, each retaining portion 24A is provided independently. The retaining portions 24A hold the area near the electrode portion 21B on the other side. Additionally, a hole 24B is provided on the end face of the retaining portion 24A. A metal contact (not shown) is mounted to the bottom retainer 24 from the side opposite to the retaining portion 24A. The contact is mounted to the bottom retainer 24 in the same manner as the contact mounted to the top retainer 23. In this embodiment, the top retainer 23 and the bottom retainer 24 correspond to the first battery retainer holding the portion of the battery 21 including the electrode portion 21B. More specifically, the top retainer 23 corresponds to the third battery retainer, and the bottom retainer 24 corresponds to the fourth battery retainer. Alternatively, the top retainer 23 may correspond to the fourth battery retainer, and the bottom retainer 24 may correspond to the third battery retainer.

[0057] As an example of a second battery holder, the intermediate holder 25 is a component that surrounds the main body of the battery 21. The main body of the battery 21 refers to the portion of the battery 21 near its center, excluding the electrode portion 21B. (See reference...) Figure 3 A and Figure 3 Section B will explain an example of the configuration of the intermediate cage 25. Figure 3 A is a three-dimensional view of the intermediate retainer 25. Figure 3 B is a top view of the intermediate retainer 25.

[0058] The intermediate retainer 25 has a sidewall portion 251 that is generally rectangular when viewed from above. On the inner side of the sidewall portion 251, retaining portions 252A and 252B are formed, with the center of the shorter side as the boundary. Retaining portion 252A has a shape that integrates 10 semi-cylindrical shapes and two generally cylindrical shapes at both ends. Each lithium-ion secondary battery cell 21A is held in place by contacting each of the cylindrical or generally cylindrical portions of the retaining portion 252A. Similarly, retaining portion 252B has a shape that integrates 10 semi-cylindrical shapes and two generally cylindrical shapes at both ends. Each of the remaining 14 lithium-ion secondary battery cells 21A is held in place by contacting each of the cylindrical or generally cylindrical portions of the retaining portion 252B.

[0059] Between the arc-shaped peripheral walls of the retaining part 252A, between the arc-shaped peripheral walls of the retaining part 252B, and between the arc-shaped peripheral walls of the retaining part 252A and the arc-shaped peripheral walls of the retaining part 252B, there are holes 253 that are roughly mountain-shaped when viewed from above. In this embodiment, 30 holes 253 are provided.

[0060] [Pool section and heat absorption section]

[0061] Next, the pool section and the heat-absorbing section will be described. The aforementioned intermediate retainer 25 has a pool section. In this embodiment, the pool section refers to the part that houses the heat-absorbing section (which may be a component or a spatial location).

[0062] Here, the heat-absorbing section is also referred to as the latent heat storage section, which is configured to absorb heat through a phase change (e.g., melting and solidification (crystallization)). Materials constituting the heat-absorbing section can include various salts such as alkali and alkaline earth hydroxides / nitrates, hydrates such as sodium acetate trihydrate, various paraffins, aluminum fatty acids, metals such as copper, magnesium nitrate hexahydrate + magnesium chloride hexahydrate, lauric acid-decanoic acid mixtures, ammonium nitrate-urea mixtures, and Fe-Co alloy single crystals such as polyethylene glycol copolymer crosslinked compounds. In this embodiment, since a rapid phase change is required to absorb the heat from the battery due to its rapid heating relative to the battery, materials with a melting point of 50°C to 60°C are preferred. Furthermore, in this embodiment, an aggregate of multiple microcapsules containing a phase change material (PCM) is used as the heat-absorbing section. Paraffin-based PCMs are preferred because they have a large latent heat. Types of microcapsules include melamine resin type and formaldehyde-free type. As to their appearance, they can be milky white slurry (a viscous liquid), thick gel, or powder.

[0063] Figure 4This is a diagram used to illustrate the pool section (pool section 255) involved in this embodiment. Figure 4 This is a top-view diagram showing the main body of the lithium-ion secondary battery cells 21A held on the intermediate holder 25. In this embodiment, a cell portion 255 is formed between the held lithium-ion secondary battery cells 21A and the hole portion 253. Figure 4 In the middle, the area at 255 in the pool section is marked with a shading line.

[0064] Next, refer to Figures 5 to 8 The heat absorption section will be explained. Figure 6 Showing a section cut along section line AA Figure 5 The sectional view shown is of the intermediate retainer 25. Figure 8 Showing a section cut along the cutting line BB Figure 7 The cross-sectional view shown is of the intermediate retainer 25. It should be noted that... Figure 5 and Figure 7 The illustration of the 21A lithium-ion secondary battery cell is omitted. Additionally, in... Figure 6 and Figure 8 In the image, a lithium-ion secondary battery cell 21A is shown using dashed lines.

[0065] like Figure 6 and Figure 8 As shown, multiple microcapsules containing phase change materials (shown as dotted lines) are contained in the pool section 255. This assembly of microcapsules functions as a heat-absorbing section 31. The heat-absorbing section 31 absorbs heat when the temperature of the battery 21 rises and releases heat when the temperature of the battery 21 cools down. This prevents the battery pack 1 from becoming excessively hot.

[0066] [Blocking Section]

[0067] Next, the blocking portion of the battery pack 1 will be described. As described above, the heat-absorbing portion 31 in this embodiment is composed of multiple microcapsules. In this embodiment, the holding portions of the top holder 23 and the bottom holder 24 are formed independently, and the holding portions are flat. Therefore, when the top holder 23, the bottom holder 24, and the intermediate holder 25 are integrated, it is possible to prevent the microcapsules constituting the heat-absorbing portion 31 from flowing into the top holder 23 and the bottom holder 24. However, there are also cases where the microcapsules are very small (e.g., 10 to 20 μm). In this case, the microcapsules may flow in through the tiny gaps between the top holder 23, the bottom holder 24, and the lithium-ion secondary battery cell 21A, and the flowing microcapsules may detour to the electrode portion 21B. As a result, micro-short circuits and poor connections between the electrode portion and the contact plate may occur. Therefore, in this embodiment, a blocking portion is provided between the electrode portion 21B and the cell portion 255 of the battery 21 to prevent the microcapsules constituting the heat-absorbing portion 31 from detouring to the electrode portion 21B. In this embodiment, the aforementioned elastic members 21C and 21D function as blocking portions.

[0068] Figure 9 This diagram illustrates an elastic member 21C according to one embodiment. It should be noted that the elastic member 21D also has the same shape as the elastic member 21C. The elastic member 21C has an annular base 211A with a circular hole 211B formed in the center. Near the periphery of the hole 211B in the base 211A, a protrusion 211C is formed that protrudes from one of the main surfaces of the base 211A.

[0069] Figure 10 and Figure 11 This diagram shows the battery 21 stored and held in the battery holder 22. It should be noted that... Figure 10 and Figure 11 For ease of understanding, the diagram shows a state in which only a portion of the lithium-ion secondary battery cells 21A constituting the battery 21 are housed and held in the battery holder 22, while the other lithium-ion secondary battery cells 21A are not housed in the battery holder 22.

[0070] As described above, the elastic member 21C is configured to surround the electrode portion 21B of the lithium-ion secondary battery cell 21A located on the top retainer 23 side. The electrode portion 21B is exposed through the hole 211B of the elastic member 21C. Similarly, the elastic member 21D is configured to surround the electrode portion 21B of the lithium-ion secondary battery cell 21A located on the bottom retainer 24 side. The electrode portion 21B is exposed through the hole of the elastic member 21D. When the battery 21 is housed and held in the top retainer 23, the electrode portion 21B and the protrusion 211C of the elastic member 21C located on the top retainer 23 side are exposed to the outside through the hole 23B of the top retainer 23. Furthermore, when the battery 21 is housed and held in the bottom retainer 24, the electrode portion 21B and the protrusion of the elastic member 21D located on the bottom retainer 24 side are exposed to the outside through the hole 24B of the bottom retainer 24.

[0071] Figure 12 Figure A is a cross-sectional view showing the state before the specified lithium-ion secondary battery cell 21A, top retainer 23, elastic member 21C, and connector 41 are installed at the end. Figure 12 Figure B is a cross-sectional view showing the state in which these components are installed. A protrusion 41A is formed on the tab 41, which is a metal plate-shaped component.

[0072] like Figure 12 As shown in Figure B, the base 211A of the elastic member 21C is flattened by the inner surface of the top retainer 23 and the lithium-ion secondary battery cell 21A. At this time, the electrode portion 21B (the positive terminal in this example) and the protrusion 211C of the elastic member 21C are exposed to the outside through the hole 23B of the top retainer 23. The protrusion 41A of the contact piece 41 is welded to the exposed electrode portion 21B. After welding, the protrusion 211C of the elastic member 21C is flattened by the contact piece 41 and the lithium-ion secondary battery cell 21A.

[0073] The elastic member 21C blocks the path between the electrode portion 21B of the lithium-ion secondary battery cell 21A and the intermediate retainer 25, in other words, the path to the electrode portion 21B. Therefore, even if the microcapsules constituting the heat-absorbing portion 31 flow in from the intermediate retainer 25 side, the microcapsules are prevented from detouring to the electrode portion 21B, thus preventing the aforementioned adverse situation from occurring.

[0074] The functions of the elastic component 21C described above also apply to the elastic components 21C and 21D of the lithium-ion secondary battery cell 21A installed in other locations.

[0075] [Effects obtained through this implementation method]

[0076] According to the above-described embodiment, the following effects can be obtained.

[0077] The heat-absorbing section can effectively cool the high-temperature battery. Furthermore, the heat-absorbing section is installed on a conventional battery holder. Therefore, it eliminates the need for additional components such as a container to house the heat-absorbing section, thus preventing the battery pack from becoming too large and suppressing weight increases. Additionally, the number of batteries does not need to be reduced when the heat-absorbing section is installed, thus preventing a decrease in volumetric energy density.

[0078] However, to effectively cool the high-temperature battery, it is desirable for the heat-absorbing part to be in contact with the battery's surroundings as much as possible. On the other hand, from the perspective of the battery pack's impact resistance and safety, it is desirable to reliably maintain the battery's structure. In this embodiment, the battery holder is divided into a top holder, a bottom holder, and a middle holder, with the top and bottom holders reliably holding the entire battery's surroundings. Furthermore, the contact area between the battery and the heat-absorbing part is maximized in the middle holder. In this way, a structure can be formed in which the top and bottom holders perform the function of holding the battery, and the middle holder performs the function of heat absorption, effectively cooling the high-temperature battery while minimizing the reduction in the battery pack's impact resistance and safety. Furthermore, by providing a blocking part, adverse situations caused by the heat-absorbing part detouring to the battery's electrode portion can be prevented.

[0079] <Variation Example>

[0080] The embodiments of the present invention have been described in detail above, but the content of the present invention is not limited to the above embodiments, and various modifications based on the technical concept of the present invention are possible.

[0081] [Example of a variation of the retaining part of the intermediate cage]

[0082] First, a modified example of the retaining part of the intermediate cage will be explained. For example... Figure 13 As shown, the intermediate retainer 25 may not be in contact with the battery 21. In this case, the area marked with a shading line in the space between each lithium-ion secondary battery cell 21A functions as the cell portion 255 according to this modification. Furthermore, microcapsules constituting the heat-absorbing portion are housed in the cell portion 255. In this modification, the assembly of microcapsules serves as both the heat-absorbing portion and the retaining portion. According to this modification, by increasing the contact area between the battery 21 and the heat-absorbing portion, the battery can be cooled more effectively.

[0083] Figure 14 This is another example of the retaining portion possessed by the intermediate retainer 25. For example... Figure 14As shown, the retaining portion (retaining portion 256) of this modified example has a generally hexagonal prism shape. The retaining portion 256 houses a lithium-ion secondary battery cell 21A. The area marked with shading lines in the space outside the retaining portion 256 functions as the cell portion 255 of this modified example. Furthermore, the cell portion 255 contains microcapsules constituting a heat-absorbing portion.

[0084] like Figure 15 As shown in Figure A, the holding portion 256 can also be a sector-shaped column formed by dividing a generally cylindrical column into four parts. The lithium-ion secondary battery cell 21A is housed inside the sector-shaped column. The space outside the holding portion 256 functions as the cell portion 255 according to this modified example. Furthermore, microcapsules constituting the heat-absorbing portion are housed in the cell portion 255.

[0085] like Figure 15 As shown in B, the holding portion 256 can also be a generally triangular prism formed by dividing a generally square prism in two. The lithium-ion secondary battery cell 21A is housed inside the generally square prism. The space outside the holding portion 256 functions as the cell portion 255 according to this modified example. Furthermore, microcapsules constituting the heat-absorbing portion are housed in the cell portion 255.

[0086] like Figure 15 As shown in C, the holding portion 256 can also be a generally regular pentagonal prism. A lithium-ion secondary battery cell 21A is housed inside the generally regular pentagonal prism. The space outside the holding portion 256 functions as the cell portion 255 according to this modified example. Furthermore, microcapsules constituting the heat-absorbing portion are housed in the cell portion 255.

[0087] It should be pointed out that, such as Figure 14 and Figure 15 A~ Figure 15 As shown in Figure C, the lithium-ion secondary battery cell 21A is preferably held in point contact with the holding portion 256. This effectively suppresses movement of the lithium-ion secondary battery cell 21A and improves its retention. Alternatively, a heat-absorbing portion may be provided inside the holding portion 256.

[0088] The retaining part 256 can also be a collection of separate rather than continuous components. For example, such as Figure 15 As shown in Figure D, the six pillars that contact each lithium-ion secondary battery cell 21A can also be holding portions 256. Through a separate configuration, the holding portions 256 have multiple slits 256A. Each lithium-ion secondary battery cell 21A can be directly contacted with the heat-absorbing portion via the slits 256A. This improves the retention of each lithium-ion secondary battery cell 21A and effectively cools the high-temperature lithium-ion secondary battery cells 21A.

[0089] [Example of a modified blocking section]

[0090] In the above embodiment, the elastic members 21C and 21D function as blocking parts, but are not limited to this. For example, the resin disposed (filled) between the top retainer and the battery, and the resin disposed between the bottom retainer and the battery, can also be blocking parts. Figure 16 As shown, for example, potting resin 51 is filled in the gap between the top retainer 23 and the designated lithium-ion secondary battery cell 21A constituting the battery 21. The cured potting resin 51 prevents the microcapsules constituting the heat-absorbing portion from detouring to the electrode portion 21B. For example, injection holes are provided in the top retainer 23 and the bottom retainer 24, through which potting resin 51 is injected. Both an elastic member and potting resin can be used as a blocking element. It should be noted that urethane resin, epoxy resin, silicone resin, acrylic resin, etc., can be used as the potting resin.

[0091] [Other variations]

[0092] Other variations will be described. In one embodiment described above, for example, a frame-shaped elastic member (an example of a second elastic member) may be disposed near the periphery where the top retainer 23 and the middle retainer 25 meet, and is flattened and clamped when the two are integrated. Alternatively, for example, a frame-shaped elastic member may be disposed near the periphery where the bottom retainer 24 and the middle retainer 25 meet, and is flattened and clamped when the two are integrated. This prevents foreign objects from entering the battery retainer 22 and prevents the microcapsules constituting the heat-absorbing part 31 from leaking out of the battery retainer 22.

[0093] The heat-absorbing part can also be in the form of a slurry or powder instead of microcapsules. Additionally, the heat-absorbing part can contain substances such as sodium bicarbonate that exhibit endothermic dehydration reactions. This further enhances the safety of the battery pack.

[0094] Alternatively, a protrusion can be formed on the periphery of the outer upper housing 10A, and a groove can be formed on the periphery of the outer lower housing 10B for the protrusion to enter, where an O-ring made of an elastic member can be housed. Thus, when the outer upper housing 10A and outer lower housing 10B are integrated, the protrusion of the outer upper housing 10A can be used to flatten the O-ring. This prevents moisture and other foreign matter from entering the outer housing 10. Furthermore, the outer housing 10 can also be a double-layered housing.

[0095] The top retainer 23, bottom retainer 24, and intermediate retainer 25 are not limited to a single retainer and can be composed of multiple retainers. The items described in the above embodiments and variations can be appropriately combined. Furthermore, the values, materials, processes, etc., described in the embodiments are merely examples, and the scope of this invention is not limited to the illustrated values, etc.

[0096] <Application Examples>

[0097] [Electric Vehicle Energy Storage System]

[0098] Next, examples of applications of the battery pack to which the present invention can be applied will be described. As an example of applying the present invention to an energy storage system for electric vehicles, Figure 17 The diagram briefly illustrates an example of a hybrid vehicle (HV) employing a series hybrid system. A series hybrid system is a vehicle that uses electricity generated by a generator powered by an engine or electricity temporarily stored in a battery to drive via an electric drive conversion device.

[0099] The hybrid vehicle 600 is equipped with an engine 601, a generator 602, an electric drive power conversion device (DC motor or AC motor, hereinafter referred to as "motor 603"), drive wheels 604a and 604b, wheels 605a and 605b, a battery 608, a vehicle control device 609, various sensors 610, and a charging port 611. The battery pack of this invention can be used as the battery 608.

[0100] The motor 603 is powered by the electricity from the storage battery 608, and the rotational force of the motor 603 is transmitted to the drive wheels 604a and 604b. The electricity generated by the generator 602 using the rotational force produced by the engine 601 is stored in the storage battery 608. Various sensors 610 control both the engine speed and the throttle opening (not shown) via the vehicle control unit 609.

[0101] When the hybrid vehicle 600 is decelerated by a braking mechanism (not shown), the resistance during deceleration is applied as a rotational force to the motor 603, and the regenerative power generated by this rotational force is stored in the battery 608. The battery 608 can be charged by connecting to an external power source via the charging port 611 of the hybrid vehicle 600. Such an HV vehicle is called a plug-in hybrid electric vehicle (PHV or PHEV).

[0102] It should be noted that the secondary battery involved in this invention can also be applied to miniaturized primary batteries as a power source for tire pressure monitoring systems (TPMS) built into wheels 604 and 605.

[0103] The above explanation uses a series hybrid vehicle as an example, but the present invention can also be applied to hybrid vehicles that use a parallel connection of the engine and motor, or a combination of series and parallel connections. Furthermore, the present invention can also be applied to electric vehicles (EVs or BEVs) and fuel cell vehicles (FCVs) that do not use an engine but only a drive motor for propulsion.

[0104] [Power tools]

[0105] Next, refer to Figure 18 As an example of an electric tool to which the present invention can be applied, an electric screwdriver will be briefly described. The electric screwdriver 831 is equipped with a motor 833 that transmits rotational power to a shaft 834 and a user-operated trigger switch 832. The battery pack 830 and motor control unit 835 of the present invention are housed in the lower frame of the handle of the electric screwdriver 831. The battery pack 830 is either built into the electric screwdriver 831 or can be detached from or installed relative to the electric screwdriver 831.

[0106] The battery pack 830 and the motor control unit 835 may each be equipped with a microcomputer (not shown), enabling them to communicate with each other regarding the charging and discharging information of the battery pack 830. The motor control unit 835 can control the operation of the motor 833 and can cut off the power supply to the motor 833 in case of abnormalities such as over-discharge.

[0107] Symbol Explanation

[0108] 1…Battery pack; 10…Outer casing; 23…Top retainer; 24…Bottom retainer; 25…Intermediate retainer; 21…Battery; 21A…Lithium-ion secondary battery cell; 21B…Electrode section; 21C, 21D…Elastic components; 31…Heat-absorbing section; 51…Pouring resin; 252A, 252B…Retaining section; 255…Cell section; 256…Retaining section; 256A…Slit.

Claims

1. A battery pack, comprising: External housing; Battery; Battery holder; and heat absorption section, The heat-absorbing section is configured to absorb heat through a phase change. The battery holder has a first battery holder and a second battery holder, the first battery holder holding the electrode portion of the battery, and the second battery holder surrounding the main body portion of the battery. The second battery holder has a pool section. The heat-absorbing part is housed in the pool section. A blocking portion is provided between the electrode portion and the pool portion. The blocking portion is composed of a first elastic member surrounding the electrode portion. The blocking portion is made of resin disposed between the first battery holder and the battery. The first elastic member has a protrusion that protrudes from one of the main surfaces of the base of the first elastic member.

2. The battery pack according to claim 1, wherein, The battery is a cylindrical battery with electrodes at both ends. The first battery holder has a third battery holder and a fourth battery holder. The third battery holder holds one of the electrode portions at both ends, and the fourth battery holder holds the other electrode portion at both ends. The second battery holder is configured to be sandwiched between the two battery holders of the first battery holder.

3. The battery pack according to claim 2, wherein, The battery holder holds a plurality of the batteries. The pool portion is formed between the plurality of batteries.

4. The battery pack according to any one of claims 1 to 3, wherein, The second battery holder has a holding portion that contacts the battery.

5. The battery pack according to claim 4, wherein, The retaining part has multiple slits.

6. The battery pack according to claim 1, wherein, The battery pack further includes tabs welded to the electrode portion. The blocking portion is flattened by the connector and the battery welded to the connector.

7. The battery pack according to any one of claims 1 to 3, wherein, The battery holder has a second elastic member that is held between the first battery holder and the second battery holder.

8. The battery pack according to any one of claims 1 to 3, wherein, The heat-absorbing part contains paraffin wax.

9. The battery pack according to any one of claims 1 to 3, wherein, The heat-absorbing part is composed of multiple microcapsules containing phase change material.

10. An electric tool having a battery pack according to any one of claims 1 to 9.

11. An electric vehicle having a battery pack according to any one of claims 1 to 9.

Images