Battery pack

Abstract

To provide a battery pack capable of preferably performing a heat transmission suppression of a cylindrical battery over a wide range.SOLUTION: In the present disclosure, a battery pack comprises: a plurality of cylindrical batteries; a heat suction member arranged between one cylindrical battery and the other cylindrical battery; and a battery holder 100 housing the plurality of cylindrical batteries and the heat suction member. The battery holder includes a surrounding part along an outer periphery of the plurality of cylindrical batteries, and is provided with a first groove extended along a shaft direction of each cylindrical battery housed by the battery holder in an inner side surface of the surrounding part of the battery holder, and a second groove extended along a circular direction of each cylindrical battery housed by the battery holder. The first and second grooves are connected.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a battery pack. [Background technology]

[0002] Patent Document 1 describes a battery pack including multiple cylindrical batteries and a battery holder, in which an air layer is formed between the outer peripheral surface of the cylindrical batteries and a vertical groove that is provided on the inner surface of the insertion portion of the battery holder into which the cylindrical batteries are inserted and that extends in the longitudinal direction of the cylindrical batteries. Patent Document 2 describes a battery module that includes a battery unit made up of two or more single cells, a housing that houses the battery unit, and a heat absorbing member that is provided in contact with the side surface of the batteries. Patent Document 2 describes that in an embodiment in which the heat absorbing member is provided between each of the single cells of the battery unit in contact with the side surface of each single cell, a recess is provided in the housing to determine the position of the heat absorbing member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-53816 A [Patent Document 2] WO2010 / 098067 issue Summary of the Invention [Problem to be solved by the invention]

[0004] Here, in the conventional technology, there are some points that need to be improved in the following respects.

[0005] Specifically, in conventional battery packs, an air layer is formed between the longitudinal grooves of the cylindrical batteries and the outer circumferential surfaces of the cylindrical batteries to block the transfer of heat from overheated cylindrical batteries and suppress heat conduction between adjacent cylindrical batteries (see Patent Document 1). However, because the location where the air layer is formed depends on the shape of the longitudinal grooves of the cylindrical batteries, it may be difficult to suppress heat conduction of cylindrical batteries over a wide range depending on the direction of heat transfer from the overheated cylindrical batteries.

[0006] In addition, in conventional battery modules in which a heat-absorbing member is provided between each cell of a battery unit in contact with the side surface of each cell (see Patent Document 2), depending on the structure of the recess in the housing in which the heat-absorbing member can be placed, it may be difficult for the heat-absorbing agent to properly absorb abnormal heat generated by a malfunctioning cell.

[0007] Therefore, an object of the present disclosure is to provide a battery pack that can suitably suppress thermal conduction of cylindrical batteries over a wide range. [Means for solving the problem]

[0008] In order to achieve the above object, the present disclosure provides: The battery includes a plurality of cylindrical batteries, a heat absorbing member disposed between one cylindrical battery and the other cylindrical battery, and a battery holder that houses the plurality of cylindrical batteries and the heat absorbing member; the battery holder has a surrounding portion that fits around the outer periphery of the cylindrical batteries; a first groove extending along the axial direction of the cylindrical battery housed in the battery holder and a second groove extending along the circumferential direction of the cylindrical battery housed in the battery holder are provided on the inner surface of the surrounding portion of the battery holder; A battery pack is provided, wherein the first groove and the second groove are connected.

[0009] In order to achieve the above object, the present disclosure provides: The battery includes a plurality of cylindrical batteries, a heat absorbing member disposed between one cylindrical battery and the other cylindrical battery, and a battery holder that houses the plurality of cylindrical batteries and the heat absorbing member; the battery holder has a surrounding portion that fits around the outer periphery of the cylindrical batteries; A plurality of protrusions are provided on an inner surface of the surrounding portion, The battery pack includes a plurality of protrusions that are provided along the circumferential direction of the cylindrical battery housed in the battery holder and along the axial direction of the cylindrical battery housed in the battery holder.

[0010] In order to achieve the above object, the present disclosure provides: The battery includes a plurality of cylindrical batteries, a heat absorbing member disposed between one cylindrical battery and the other cylindrical battery, and a battery holder that houses the plurality of cylindrical batteries and the heat absorbing member; the battery holder has a surrounding portion that fits around the outer periphery of the cylindrical batteries; a plurality of protrusions are provided on the inner surface of the surrounding portion of the battery holder; a first groove extending along the axial direction of the cylindrical battery housed in the battery holder; and a second groove extending along the circumferential direction of the cylindrical battery housed in the battery holder. A battery pack is provided, wherein the protrusion has a portion surrounded by the first groove and the second groove. Effect of the Invention

[0011] According to the battery pack of the present disclosure, it is possible to effectively suppress the heat conduction of cylindrical batteries over a wide range. [Brief description of the drawings]

[0012] [Figure 1] 1 is an exploded perspective view showing a schematic diagram of a battery pack according to a first embodiment of the present disclosure. [Diagram 2] FIG. 2 is an exploded perspective view showing a schematic diagram of a core pack in the battery pack of the first embodiment. [Diagram 3]3 is a cross-sectional view showing a schematic positional relationship between a battery holder and a heat absorbing member in the battery pack of the first embodiment. FIG. [Figure 4] 2 is a cross-sectional view showing a schematic view of the battery holder taken along line AA in FIG. 1. [Diagram 5] 3 is a cross-sectional view showing a schematic diagram of a first battery holder part in the battery pack of the first embodiment. FIG. [Figure 6] 6 is a front view showing a schematic view of the first battery holder part as viewed from an angle different from that in FIG. 5. [Figure 7] 4 is a cross-sectional view showing a schematic diagram of a second battery holder part in the battery pack of the first embodiment. FIG. [Figure 8] 8 is a front view showing a schematic view of the second battery holder part as viewed from an angle different from that in FIG. 7. FIG. [Figure 9] 4A and 4B are schematic diagrams showing how a first groove and a second groove are formed in a battery holder using multiple battery holder parts in the battery pack of the first embodiment. [Figure 10] 2 is a cross-sectional view showing a schematic view of a battery holder taken along line AA in FIG. 1 in a battery pack according to a second embodiment of the present disclosure. [Figure 11] 13 is a schematic diagram showing a formation mode of a first groove and a second groove of a battery holder using multiple battery holder parts in a battery pack according to a second embodiment. FIG. [Figure 12] 13 is a schematic diagram showing a formation mode of a first groove and a second groove of a battery holder using multiple battery holder parts in a battery pack of a third embodiment. FIG. [Figure 13] 13 is a schematic diagram showing a formation mode of a first groove and a second groove of a battery holder using multiple battery holder parts in a battery pack according to a fourth embodiment. FIG. [Figure 14] 13 is a schematic diagram showing a formation mode of a first groove and a second groove of a battery holder using multiple battery holder parts in a battery pack according to a fifth embodiment. FIG. [Figure 15] 13 is a schematic diagram showing a formation mode of a first groove and a second groove of a battery holder using multiple battery holder parts in a battery pack of a sixth embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] A battery pack according to an embodiment of the present disclosure will be specifically described below with reference to the drawings. Although the description will be made with reference to the drawings as necessary, various elements in the drawings are merely shown as schematic examples for understanding the present disclosure, and the appearances and dimensional ratios may differ from the actual ones.

[0014] Various numerical ranges mentioned in this specification are intended to include the lower and upper limit numerical values ​​themselves, unless a special term such as "less than" or "more than / greater than" is added. In other words, for example, a numerical range such as 1 to 10 can be interpreted as including the lower limit of "1" and the upper limit of "10". In addition, terms such as "about" and "approximately" mean that the range may include a variation of a few percent, for example, ±10%.

[0015] In this specification, the term "plan view" refers to the state when an object (e.g., a battery pack) is placed and viewed from directly above in the thickness (height) direction. In this specification, the term "side view" refers to the state when an object (e.g., a battery pack) is placed and viewed from the side perpendicular to the thickness (height) direction, unless otherwise specified. In this specification, the term "front view" refers to the state when an object (e.g., a battery pack) is placed and viewed from the axial direction of a cylindrical cell, unless otherwise specified.

[0016] [First embodiment] The overall configuration of the battery pack according to the first embodiment of the present disclosure will be described below. Fig. 1 is an exploded perspective view that typically shows the battery pack according to the first embodiment of the present disclosure. Fig. 2 is an exploded perspective view that typically shows the core pack in the battery pack according to the first embodiment. Fig. 3 is a cross-sectional view that typically shows the positional relationship between the battery holder and the heat absorbing member in the battery pack according to the first embodiment.

[0017] As shown in Figures 1 and 2, the battery pack 1000 of the first embodiment comprises a plurality of cylindrical batteries 200, a battery holder 100 capable of accommodating at least a plurality of cylindrical batteries 200, tabs 400 that electrically connect the cylindrical batteries 200, a substrate 500 connected to the tabs, and an exterior body 600 that accommodates the integrated assembly (hereinafter referred to as a battery core pack).

[0018] The exterior body 600 may have a main body and a lid that can be combined with the main body. The exterior body 600 is provided with an external terminal 610 connected to a substrate 500. A plurality of cylindrical batteries 200 (described below) are connected to the external terminal 610 via the substrate 500. In addition to the plurality of cylindrical batteries 200 described above, the battery holder 100 can also accommodate a heat absorption member 300 that is disposed between one cylindrical battery 200 and the other cylindrical battery 200.

[0019] (Cylindrical battery) 2, the cylindrical battery 200 is accommodated in a housing portion (described later) of the above-mentioned battery holder 100. The cylindrical battery 200 accommodates electrodes in a cylindrical, bottomed exterior can 201, which is filled with an electrolyte and has an opening closed by a sealing plate 202. The cylindrical battery 200 has positive and negative electrode terminals at the bottom surface of the exterior can 201, which are both end surfaces, and electrodes provided on the sealing plate 202. For example, the cylindrical battery 200 can be a lithium ion secondary battery that can be charged and discharged.

[0020] With respect to the cylindrical battery 200 designated by the reference numeral 200 explained based on FIG. 2 above, even if no specific reference numeral is given hereinafter in this specification, the cylindrical battery refers to the battery designated by the reference numeral 200 (see FIG. 2).

[0021] (battery holder) 2 and 3, the battery holder 100 has multiple storage sections 101 capable of accommodating each cylindrical battery 200 so that the multiple cylindrical batteries 200 can be arranged in parallel adjacent to one another, and an enclosure section 102 that defines at least a portion of each storage section 101 (see FIG. 3 in particular). In this specification, the enclosure section 102 can also be referred to as a housing section, main body section, body section, or wall section.

[0022] In the surrounding portion 102 of the housing portion 101, a predetermined portion of the surrounding portion 102 located between adjacent cylindrical batteries 200 functions as a partition between the cylindrical batteries 200. The housing portion 101 is a space capable of housing the cylindrical batteries 200. As an example, when the surrounding portion defines a portion of the housing portion 101, the heat absorbing member 300 disposed in the battery holder 100 can define the remainder of the housing portion 101 other than the surrounding portion 102 or other portions of the housing portion 101. In other words, the heat absorbing member 300 and the surrounding portion 102 of the battery holder 100 are responsible for the outline of the housing portion 101 that houses each cylindrical battery 200. In this case, most of the outline of the housing portion 101 can be continuous.

[0023] The shape of the surrounding portion 102 of the battery holder 100 and the shape of the outer surface of the heat absorption member 300 depend on the cross-sectional shape of the cylindrical battery 200 to be housed or inserted. For example, as shown in Fig. 2, if the cross-sectional shape of the cylindrical battery 200 is a perfect circle, the shape of the surrounding portion 102 of the battery holder 100 and the shape of the outer surface of the heat absorption member 300 can also have a curved shape corresponding to the perfect circle. Also, if the cross-sectional shape of the cylindrical battery 200 is an ellipse, the shape of the surrounding portion 102 of the battery holder 100 and the shape of the outer surface of the heat absorption member 300 can also have a curved shape corresponding to the ellipse.

[0024] 2 coincides with the central axis of the space in the storage section 101. In this case, when the cylindrical batteries 200 are stored in the storage section 101, the distance between the central axis of one adjacent cylindrical battery 200 and the central axis of the other cylindrical battery 200 is unlikely to change, making it easy to perform tab attachment using tabs 400 that electrically connect the cylindrical batteries 200 to each other, as described below.

[0025] In view of the above, when the cylindrical battery 200 is placed in the storage section 101 of the battery holder 100, the cylindrical battery 200, the heat absorption member 300 and the enclosing section 102 of the battery holder 100 can be positioned so that the outer circumferential circumference of the cylindrical battery 200 can face each of the enclosing section 102 of the battery holder 100 and the heat absorption member 300 provided adjacent to the enclosing section 102 in the same circumferential direction.

[0026] The battery holder 100 is molded into a predetermined shape from an insulating material such as thermoplastic resin, etc. As such a resin, for example, PC (polycarbonate) or PP (polypropylene) can be used.

[0027] (tab) The tabs 400 are housed in the housing portion 101 and electrically connect adjacent cylindrical batteries 200 to each other. The tabs 400 may electrically connect the cylindrical batteries 200 in series or in parallel. To achieve such electrical connection, the tabs 400 are preferably made of a material with good electrical conductivity. As an example, metal is preferable.

[0028] (Exterior body) The exterior body 600 may be any body capable of stably housing the above-mentioned battery core pack. In addition, it is preferable to use an insulating material in consideration of the safety of the battery pack. Furthermore, the exterior body 600 may be provided with a connector or the like for extracting the power generated by the cylindrical battery 200 housed therein.

[0029] (Characteristic parts of the first embodiment) After describing the overall configuration above, the following describes the characteristic parts of the first embodiment of the present disclosure. The first embodiment of the present disclosure is characterized by the configuration of the battery holder 100 described above.

[0030] Specifically, in the battery holder 100, a first groove 103 and a second groove 104 are provided on an inner surface 106 of an enclosure 102 that fits around the outer periphery of multiple cylindrical batteries 200, and the first groove 103 and the second groove 104 are connected to each other. In this specification, the "inner surface of the enclosure of the battery holder" can also be referred to as the inner main surface or the inner side surface. In this embodiment, the width of the first groove 103 and the width of the second groove 104 can be approximately the same, or the width of the second groove 104 can be less than twice the width of the first groove 103. The width of the second groove 104 may be narrower than the width of the first groove 103.

[0031] The "inner surface of the battery holder" here refers to the side surface located inside the battery holder enclosure 102. Additionally, the "first groove 103" here refers to a groove that extends along the axial direction of the cylindrical battery 200 housed in the battery holder 100 (see FIG. 1), and the "second groove 104" refers to a groove that extends along the circumferential direction of the cylindrical battery 200 housed in the battery holder 100 (see FIG. 1).

[0032] The first groove 103 and the second groove 104 can be formed by a plurality of protrusions 105 provided on the inner surface 106 of the surrounding portion 102 of the battery holder 100 .

[0033] Specifically, as shown in Fig. 4, multiple protrusions 105 are provided along the circumferential direction of the cylindrical battery 200 housed in the battery holder 100, and also along the axial direction of the cylindrical battery 200 housed in the battery holder 100. In other words, multiple protrusions 105 are provided along both the circumferential direction and the axial direction.

[0034] As an example, as shown in Fig. 4, adjacent protrusions 105a, 105c are arranged at a predetermined interval in the axial direction of cylindrical battery 200, and a second groove 104 is formed between these protrusions. Also, adjacent protrusions 105a, 105b are arranged at a predetermined interval in the circumferential direction of cylindrical battery 200, and a first groove 103 is formed between these protrusions. Since the first groove 103 and the second groove 104 are formed between two adjacent protrusions at a predetermined interval, the first groove 103 and the second groove 104 can also be called a first recess and a second recess, respectively.

[0035] In a configuration in which the inner surface 106 of the enclosing portion 102 of the above-mentioned battery holder 100 is provided with a plurality of protrusions 105, a first groove 103, and a second groove 104, from another perspective, the battery pack of the present disclosure is characterized in that the protrusion 105 has a portion surrounded by the first groove 103 and the second groove 104.

[0036] In addition, in the present disclosure, the heat absorbing member 300 described above has an endothermic agent and an exterior material containing the endothermic agent. As an example, the endothermic agent can be contained by fusing two mutually opposing exterior materials. With the structure of such an exterior material, it is possible to prevent the internal endothermic agent from leaking out except when the cylindrical battery 200 at a predetermined location generates abnormal heat, as described below. In other words, with the structure of the exterior material of the heat absorbing member 300 described above, the internal endothermic agent can be stably held and high safety can be ensured for a long period of time.

[0037] The heat absorbing agent is mainly composed of a liquid such as water, and may contain a gelling agent for easy handling and a surfactant for improving hydrophilicity. As the gelling agent, polyvinyl alcohol or the like may be used. The content of the liquid such as water in the heat absorbing agent may be, for example, 50% by weight to 99% by weight. Although not particularly limited, the exterior material may have a metal layer and different types of resin layers arranged on both main surfaces of the metal layer. The metal material is formed of, for example, an Al layer. The first resin layer may be made of polyethylene terephthalate (PET), and the second resin layer may be made of polyethylene. The thickness of the metal material layer and each resin layer may be about several tens of μm.

[0038] The following describes the function and effect of the heat absorbing member 300 when a cylindrical battery 200 at a specific location abnormally heats up. When a cylindrical battery 200 at a specific location abnormally heats up, the heat absorbing agent inside the heat absorbing member close to the abnormally heat-generating part of the battery expands, causing the internal pressure to rise. This causes the heat absorbing member 300 to split, allowing the heat absorbing agent to be released to the outside starting from the split point.

[0039] Specifically, as described above, the heat absorbing member 300 and the surrounding portion 102 of the battery holder 100 form the outline of the housing portion 101 that houses the cylindrical battery 200. In this case, the heat absorbing member 300 and the inner surface 106 of the surrounding portion 102 are disposed adjacent to each other. Furthermore, the first groove 103 and the second groove 104, which are provided on the inner surface 106 of the surrounding portion 102 and connected to each other, extend in different directions, and therefore can take an intersecting form. From another perspective, the first groove 103 and the second groove 104 extend in different directions, and therefore as a whole, form a groove having a bent form.

[0040] By adopting the above-mentioned configuration, the first groove 103 and the second groove 104 can both function as grooves through which the heat absorbing agent contained in the heat absorbing member provided inside the battery holder 100 can pass. This allows the heat absorbing agent to spread around the outer periphery of the cylindrical battery 200 along the axial and circumferential directions of the cylindrical battery 200. As a result, not only can the abnormally heated portion be locally cooled, but the cylindrical battery 200 can be cooled over a wide area.

[0041] 2 and 3, in an embodiment in which a heat absorbing member 300 is disposed between one cylindrical battery 200 and the other cylindrical battery 200, it is possible to reduce heat transfer from the cleavage point of the heat absorbing member 300 to multiple cylindrical batteries 200 adjacent to the location where the heat absorbing member 300 is disposed (including the cylindrical battery 200 that has generated abnormal heat, as well as other adjacent cylindrical batteries 200 that are not generating abnormal heat). As a result, it is possible to prevent chain reaction heating of other cylindrical batteries 200 that are not generating abnormal heat and that are positioned within the battery holder 100, and to minimize malfunctions of the battery pack 1000. In other words, it is possible to preferably suppress heat transfer between multiple cylindrical batteries 200.

[0042] In addition, the heat absorbing agent can cool high-temperature gas that may be emitted from an abnormally heated cylindrical battery 200 to below the flash point. Therefore, the emitted gas can be exhausted to the outside of the battery pack 1000 at a temperature below the flash point through, for example, the ventilation member 610 of the exterior body 600. In other words, the emitted gas can be exhausted to the outside of the battery pack 1000 while preventing the generation of flames due to ignition.

[0043] For these reasons, even in a configuration in which the heat absorption member 300 is positioned locally between one cylindrical battery 200 and the other cylindrical battery 200, the battery pack of the first embodiment is superior to conventional ones in that it is possible to optimally cool the cylindrical batteries 200 over a wide area through the above-mentioned two types of grooves, and further to prevent the chain reaction of heating of other cylindrical batteries 200 that are not generating abnormal heat.

[0044] It is preferable that a plurality of the first grooves 103 and a plurality of the second grooves 104 are provided. When there are a plurality of first grooves extending in the axial direction of the cylindrical battery 200 and a plurality of second grooves extending in the circumferential direction, the number of routes for distributing the heat absorbing agent to the outer periphery of the cylindrical battery 200 along the axial and circumferential directions of the cylindrical battery 200 can be increased. As a result, the cylindrical battery 200 can be appropriately cooled over a wider range.

[0045] The characteristic configuration of the battery holder 100 in the first embodiment will be described below.

[0046] Fig. 4 is a cross-sectional view showing a battery holder taken along line AA in Fig. 1. Fig. 5 is a cross-sectional view showing a first battery holder part in the battery pack of the first embodiment. Fig. 6 is a front view showing the first battery holder part from an angle different from that in Fig. 5. Fig. 7 is a cross-sectional view showing a second battery holder part in the battery pack of the first embodiment. Fig. 8 is a front view showing the second battery holder part from an angle different from that in Fig. 7. Fig. 9 is a schematic diagram showing the formation of the first and second grooves in a battery holder using multiple battery holder parts in the battery pack of the first embodiment.

[0047] As shown in Figures 2 and 4, the battery holder 100 in the first embodiment is composed of battery holder components 110, 120 that are divided into multiple pieces in the axial direction of the cylindrical battery 200 housed in the battery holder 100. In other words, the battery holder 100 is composed of multiple battery holder components 110, 120 that are connected to each other along the axial direction. In the example shown in Figure 4, a first battery holder component 110, a second battery holder component 120, a second battery holder component 120, and a first battery holder component 110 are connected to each other in this order along the axial direction. In addition, each battery holder component has a row of protrusions 105 at predetermined intervals along the circumferential direction.

[0048] The "first battery holder part 110" referred to here is a component (holder part) of the battery holder 100 that can receive both axial ends of a cylindrical battery, and that has one axial side that is completely open and the other side that has a receiving section that can receive a cylindrical battery and a partial opening for the internal cylindrical battery to come into contact with a tab (see Figures 5 and 6). This first battery holder part 110 has a sub-groove 103a that is part of the first groove 103 and a sub-groove 104a that is part of the second groove 104.

[0049] The "second battery holder part 120" referred to here is a component (holder part) of the battery holder 100 in the form of a through hole capable of receiving the middle part of a cylindrical battery in the axial direction (see Figs. 7 and 8). This second battery holder part 120 has a sub-groove 103b that forms part of the first groove 103 and a sub-groove 104b that forms part of the second groove 104. In this configuration, the width of the sub-groove that forms part of the second groove 104 and the sub-groove that forms part of the first groove 103 may be the same or approximately the same.

[0050] Moreover, the above-mentioned multiple battery holder parts 110, 120 are arranged in series. In such a configuration, the second groove 104 may be formed of one battery holder part and the other battery holder part connected to each other along the axial direction. In one example, the second groove 104 may be formed at the interconnection point between the first battery holder part 110 and the second battery holder part 120 (see FIG. 9 ). In another example, the second groove 104 may be formed at the interconnection point between the second battery holder part 120 and the second battery holder part 120.

[0051] The second to sixth embodiments will be described below. In order to avoid duplication, the following description will focus on the differences between the first and second embodiments.

[0052] [Second embodiment] A characteristic configuration of the battery pack according to the second embodiment of the present disclosure will be described below.

[0053] Fig. 10 is a cross-sectional view showing a battery holder in a battery pack according to a second embodiment of the present disclosure taken along line AA in Fig. 1. Fig. 11 is a schematic diagram showing a formation mode of a first groove and a second groove in a battery holder using multiple battery holder parts in a battery pack according to the second embodiment.

[0054] The second embodiment differs from the first embodiment in that, from the viewpoint of the grooves, the width W2 of the second groove on the inner surface 106A of the surrounding portion of the battery holder 100A is larger than the width W1 of the first groove (see FIGS. 10 and 11). As an example, the width of the second groove 104A is more than twice the width of the first groove 103A, and can be, for example, 3 to 4 times.

[0055] From the perspective of the protrusions, the distance W2 between the multiple protrusions 105Aa, 105Ac arranged along the axial direction of the cylindrical battery housed in the battery holder 100A is wider than the distance W1 between the multiple protrusions 105Aa, 105Ab arranged along the circumferential direction of the cylindrical battery housed in the battery holder 100A.

[0056] In the second embodiment, a first battery holder part 110A, which is a component of a battery holder 100A, has a sub-groove that is part of the first groove and a sub-groove 104Aa that is part of the second groove 104A. A second battery holder part 120A has a sub-groove that is part of the first groove and a sub-groove 104Ab that is part of the second groove 104A. The width of the sub-groove that is part of the second groove 104A is larger than the width of the sub-groove that is part of the first groove.

[0057] In such a configuration, the second groove 104A may be formed between one battery holder part and the other battery holder part that are connected to each other along the axial direction. In one example, the second groove 104A may be formed at the interconnection point between the first battery holder part 110A and the second battery holder part 120A (see FIG. 11). In another example, the second groove 104A may be formed at the interconnection point between the second battery holder part 120A and the second battery holder part 120A (see FIG. 10).

[0058] According to the above feature, the width W2 of the second groove 104A on the inner surface 106A of the battery holder 100A is larger than the width W1 of the first groove 103A, or the distance W2 between the multiple protrusions 105Aa, 105Ac is larger than the distance W1 between the multiple protrusions 105Aa, 105Ab. Therefore, the heat absorbing agent can be more effectively distributed around the outer periphery of the cylindrical battery, particularly along the circumferential direction of the cylindrical battery. That is, the heat absorbing agent can be easily spread in the circumferential direction. This makes it possible to more effectively suppress heat transfer to adjacent cylindrical batteries compared to the first embodiment.

[0059] [Third embodiment] The characteristic configuration of the battery pack according to the third embodiment of the present disclosure will be described below. Fig. 12 is a schematic diagram of the formation of the first groove and the second groove of the battery holder using multiple battery holder parts in the battery pack according to the third embodiment.

[0060] The third embodiment differs from the first embodiment in terms of grooves in that the second grooves on the inner surface of the battery holder are connected to multiple mutually different points of the first groove (see FIG. 12).

[0061] 12, when one first groove 103B extending along the axial direction is considered, one end of the first groove 103B is connected to one second groove 104B1, and the other end of the first groove is connected to the other second groove 104B3. Also, a second groove 104B2 is connected to a predetermined region (near the center region) of the first groove 103B.

[0062] In terms of the protrusions, the multiple protrusions 105B1, 105B2 provided along the circumferential direction of the cylindrical battery housed in the battery holder are provided in positions where the multiple protrusions are staggered when viewed from the circumferential direction of the cylindrical battery (see FIG. 12).

[0063] In this configuration, the longitudinally extending portions of the second grooves 104B1-104B3 face the protrusions 105B1 and 105B2. Due to this facing relationship, the heat absorbing agent ejected from inside the heat absorbing member can first come into contact with the surfaces, particularly the side surfaces, of the protrusions 105B1 and 105B2.

[0064] At such contact points, due to the presence of the convex portions 105B1 and 105B2, the heat absorbing member cannot move continuously along the longitudinal direction of the second grooves 104B1-104B3, and part of it may move along the first groove 103B that intersects with the second grooves 104B1-104B3.

[0065] In this regard, in the first embodiment, the portion extending in the longitudinal direction of the groove and the protrusion are not in a positional relationship in which they directly face each other, so that the heat absorbing agent can move continuously along the longitudinal direction of the groove. In contrast, in the third embodiment, compared to the first embodiment, the heat absorbing agent moving along the longitudinal direction of the second grooves 104B1-104B3 is divided into one moving along the second groove and one moving along the first groove, starting from the contact point. That is, compared to the first embodiment, the movement path of the heat absorbing agent can be branched starting from the contact point, and as a result, the number of movement paths of the heat absorbing agent can be increased.

[0066] As a result, compared to the first embodiment, the heat absorbing agent can be diffused radially from the contact points through the second grooves 104B1-104B3 and the first groove 103B. As a result, the abnormally heated portion of the cylindrical battery and its vicinity can be cooled efficiently and effectively.

[0067] [Fourth embodiment] A characteristic configuration of the battery pack according to the fourth embodiment of the present disclosure will be described below. Fig. 13 is a schematic diagram of a formation mode of the first groove and the second groove of the battery holder using multiple battery holder parts in the battery pack according to the fourth embodiment.

[0068] The fourth embodiment differs from the first embodiment in that, from the viewpoint of grooves, multiple second grooves 104C1, 104C2 on the inner surface of the battery holder are connected to predetermined locations of the first groove 103C (see FIG. 13). Specifically, as shown in FIG. 13, one second groove 104C1 and the other second groove 104C2 are each connected to one end of the first groove 103C.

[0069] In terms of the protrusions, the multiple protrusions 105C1, 105C2 arranged along the axial direction of the cylindrical battery housed in the battery holder are arranged in positions where the multiple protrusions 105C1, 105C2 are staggered when viewed from the axial direction of the cylindrical battery (see Figure 13).

[0070] In this configuration, the longitudinally extending portion of the first groove 103C faces the protrusions 105C1 and 105C2. Due to this facing relationship, the heat absorbing agent ejected from inside the heat absorbing member can first come into contact with the surfaces, particularly the side surfaces, of the protrusions 105C1 and 105C2.

[0071] At such contact points, due to the presence of the above-mentioned convex portions 105C1 and 105C2, the heat absorption member cannot move continuously along the longitudinal direction of the first groove 103C, but a portion of the heat absorption member intersects with the first groove 103C and can move along the second grooves 104C1 and 104C2 which are interconnected and integrated.

[0072] In this regard, in the first embodiment, the portion extending in the longitudinal direction of the first groove and the protruding portion are not in a positional relationship in which they directly face each other, so the heat absorbing agent can move continuously along the longitudinal direction of the first groove. In contrast, in the fourth embodiment, compared to the first embodiment, the heat absorbing agent moving along the longitudinal direction of the first groove 103C is divided into one moving along the first groove and one moving along the second groove, starting from the contact point. That is, compared to the first embodiment, the movement path of the heat absorbing agent can be branched starting from the contact point, and as a result, the number of movement paths of the heat absorbing agent can be increased.

[0073] As a result, compared to the first embodiment, the heat absorbing agent can be diffused radially from the contact point through the first groove 103C and the second grooves 104C1 and 104C2. As a result, the abnormally heated portion of the cylindrical battery and its vicinity can be cooled efficiently and effectively.

[0074] [Fifth embodiment] The following describes a characteristic configuration of the battery pack according to the fifth embodiment of the present disclosure. Fig. 14 is a schematic diagram of the formation of the first and second grooves of the battery holder using multiple battery holder parts in the battery pack according to the fifth embodiment.

[0075] The fifth embodiment is a modification of the fourth embodiment. Specifically, like the fourth embodiment, the fifth embodiment has multiple protrusions 105D1, 105D2 arranged along the axial direction of the cylindrical battery housed in the battery holder, and are arranged at alternating positions when viewed from the axial direction of the cylindrical battery (see FIG. 14).

[0076] On the other hand, when viewed in the thickness direction of the cylindrical battery (also see Figure 2), the shape of the convex portion tapers from the first battery holder part 110D to the second battery holder part 120D. In other words, the first groove 103D has a reverse tapered shape.

[0077] This causes the width of the first groove to vary gradually, which increases the flow rate of the heat absorbing agent when it is radially diffused through the groove starting from the cleavage point of the heat absorbing member. As a result, the heat absorbing agent can be distributed farther from the cleavage point over a wider range around the outer periphery of the cylindrical battery.

[0078] [Sixth embodiment] A characteristic configuration of the battery pack according to the sixth embodiment of the present disclosure will be described below. Fig. 15 is a schematic diagram of a formation mode of the first groove and the second groove of the battery holder using multiple battery holder parts in the battery pack according to the sixth embodiment.

[0079] The sixth embodiment is a modification of the fourth embodiment. Specifically, like the fourth embodiment, the sixth embodiment has multiple protrusions 105E1, 105E2 arranged along the axial direction of the cylindrical battery housed in the battery holder, and are arranged at alternating positions when viewed from the axial direction of the cylindrical battery (see FIG. 15).

[0080] On the other hand, when viewed from the thickness direction of the cylindrical battery (also see FIG. 2), the shape of the protrusions is circular or semicircular. That is, the protrusions 105E1 and 105E2 do not have bent portions and are curved (corresponding to an R-shape).

[0081] The shape of the protrusions reduces the pressure loss that may occur when the heat absorbing agent ejected from inside the heat absorbing member comes into contact with the surface, especially the side surface, of the protrusions. This increases the flow rate of the heat absorbing agent when it is diffused radially through the grooves starting from the cleavage point of the heat absorbing member. As a result, the heat absorbing agent can be diffused farther over a wider range around the outer periphery of the cylindrical battery starting from the cleavage point.

[0082] It should be noted that the embodiments disclosed herein are illustrative in all respects and are not intended to be limiting. Therefore, the technical scope of the present disclosure is not interpreted solely by the above-described embodiments, but is defined based on the claims. The technical scope of the present disclosure also includes all modifications within the scope and meaning equivalent to the claims.

[0083] The battery pack of the present disclosure includes the following aspects. <1> The battery includes a plurality of cylindrical batteries, a heat absorbing member disposed between one cylindrical battery and the other cylindrical battery, and a battery holder that houses the plurality of cylindrical batteries and the heat absorbing member; the battery holder has a surrounding portion that fits around the outer periphery of the cylindrical batteries; a first groove extending along the axial direction of the cylindrical battery housed in the battery holder and a second groove extending along the circumferential direction of the cylindrical battery housed in the battery holder are provided on the inner surface of the surrounding portion of the battery holder; The first groove and the second groove are connected to each other. <2> A plurality of the first grooves are provided, and a plurality of the second grooves are provided. <1> The battery pack according to claim 1 . <3> The width of the second groove is greater than the width of the first groove. <1> or <2> The battery pack according to claim 1 . <4> The second groove is connected to a plurality of mutually different points of the first groove, <1> ~ <3> 13. The battery pack according to claim 12, <5> One end of the first groove is connected to one second groove, and the other end of the first groove is connected to the other second groove. <4> The battery pack according to claim 1 . <6> A plurality of the second grooves are connected to predetermined locations of the first groove. <1> ~ <5> 13. The battery pack according to claim 12, <7> One end of the first groove is connected to one second groove and the other second groove is connected to the other end of the first groove. <6> The battery pack according to claim 1 . <8> The battery includes a plurality of cylindrical batteries, a heat absorbing member disposed between one cylindrical battery and the other cylindrical battery, and a battery holder that houses the plurality of cylindrical batteries and the heat absorbing member; the battery holder has a surrounding portion that fits around the outer periphery of the cylindrical batteries, and a plurality of protrusions are provided on an inner surface of the surrounding portion; The battery pack, wherein the multiple protrusions are provided along a circumferential direction of the cylindrical battery housed in the battery holder and along an axial direction of the cylindrical battery housed in the battery holder. <9> the distance between multiple protrusions arranged along the axial direction of the cylindrical battery housed in the battery holder is greater than the distance between multiple protrusions arranged along the circumferential direction of the cylindrical battery housed in the battery holder; <8> The battery pack according to claim 1 . <10> the multiple protrusions provided along the circumferential direction of the cylindrical battery housed in the battery holder are provided in positions that are staggered when viewed from the circumferential direction of the cylindrical battery; <8> or <9> The battery pack according to claim 1 . <11> the multiple protrusions provided along the axial direction of the cylindrical battery housed in the battery holder are provided in positions that are staggered when viewed from the axial direction of the cylindrical battery; <8> ~ <10> 13. The battery pack according to claim 12, <12> the battery holder is composed of a plurality of battery holder parts that are divided in the axial direction of the cylindrical battery that is accommodated in the battery holder; <1> ~ <11> 13. The battery pack according to claim 12, <13> The second groove is formed by one of the battery holder parts and the other of the battery holder parts connected to each other along the axial direction. <12> The battery pack according to claim 1 . <14> A plurality of the battery holder parts are arranged in series. <12> or <13> The battery pack according to claim 1 . <15> The first groove and the second groove form a bent groove. <1> ~ <7> , <12> ~ <14> 13. The battery pack according to claim 12, <16> The first groove and the second groove intersect. <1> ~ <7> , <12> ~ <15> 13. The battery pack according to claim 12, <17> The battery includes a plurality of cylindrical batteries, a heat absorbing member disposed between one cylindrical battery and the other cylindrical battery, and a battery holder that houses the plurality of cylindrical batteries and the heat absorbing member; the battery holder has a surrounding portion that fits around the outer periphery of the cylindrical batteries; a plurality of protrusions are provided on the inside surface of the surrounding portion of the battery holder; a first groove extending along the axial direction of the cylindrical battery housed in the battery holder; and a second groove extending along the circumferential direction of the cylindrical battery housed in the battery holder. the protrusion has a portion surrounded by the first groove and the second groove. <18> A portion of the first groove or the second groove extending in the longitudinal direction faces the protrusion. <17> The battery pack according to claim 1 . [Industrial Applicability]

[0084] The battery pack of the present disclosure can be used primarily as a power source for motive power, for example, for electric devices driven by a motor, such as power tools and power-assisted bicycles. [Explanation of symbols]

[0085] 100, 100A Battery Holder 101 Storage unit 102 Wall 103, 103A~103D First groove 103a Sub-groove 103b Sub-groove 104, 104A, 104B1~104B3, 104C1, 104C2 Second groove 104a, 104Aa sub-groove 104b, 104Ab subgroove 105, 105a, 105b, 105c convex part 105A, 105Aa, 105Ab, 105Ac Convex 105B1, 105B2 convex part 105C1, 105C2 convex part 105D1, 105D2 convex part 105E1, 105E2 convex part 106, 106A Battery holder inner wall 110, 110A~110E Battery holder parts 120, 120A~120E Battery holder parts 200 Cylindrical Battery 201 Outer can 202 Sealing plate 300 Heat absorbing member 400 Tab 500 boards 600 Exterior 1000 Battery Packs W1 Width of the first groove on the inner wall of the battery holder W2 Width of the second groove on the inner wall of the battery holder

Claims

1. The battery includes a plurality of cylindrical batteries, a heat absorbing member disposed between one cylindrical battery and the other cylindrical battery, and a battery holder that houses the plurality of cylindrical batteries and the heat absorbing member; the battery holder has a surrounding portion that fits around the outer periphery of the cylindrical batteries; a first groove extending along the axial direction of the cylindrical battery housed in the battery holder and a second groove extending along the circumferential direction of the cylindrical battery housed in the battery holder are provided on the inner surface of the surrounding portion of the battery holder; The first groove and the second groove are connected to each other.

2. The battery pack according to claim 1 , wherein a plurality of the first grooves are provided, and a plurality of the second grooves are provided.

3. The battery pack according to claim 1 , wherein a width of the second groove is greater than a width of the first groove.

4. The battery pack according to claim 1 , wherein the second groove is connected to a plurality of mutually different points of the first groove.

5. 5. The battery pack according to claim 4, wherein one end of the first groove is connected to one of the second grooves, and the other end of the first groove is connected to the other of the second grooves.

6. The battery pack according to claim 1 , wherein a plurality of the second grooves are connected to the first groove at predetermined locations.

7. 7. The battery pack according to claim 6, wherein one end of the first groove is connected to one of the second grooves and the other of the second grooves.

8. The battery includes a plurality of cylindrical batteries, a heat absorbing member disposed between one cylindrical battery and the other cylindrical battery, and a battery holder that houses the plurality of cylindrical batteries and the heat absorbing member; the battery holder has a surrounding portion that fits around the outer periphery of the cylindrical batteries; A plurality of protrusions are provided on an inner surface of the surrounding portion, The battery pack, wherein the multiple protrusions are provided along a circumferential direction of the cylindrical battery housed in the battery holder and along an axial direction of the cylindrical battery housed in the battery holder.

9. 9. The battery pack according to claim 8, wherein the distance between multiple protrusions arranged along the axial direction of the cylindrical battery housed in the battery holder is greater than the distance between multiple protrusions arranged along the circumferential direction of the cylindrical battery housed in the battery holder.

10. 9. The battery pack according to claim 8, wherein the plurality of protrusions provided along the circumferential direction of the cylindrical battery housed in the battery holder are provided in positions such that the plurality of protrusions are staggered when viewed from the circumferential direction of the cylindrical battery.

11. 9. The battery pack according to claim 8, wherein the plurality of protrusions provided along the axial direction of the cylindrical battery housed in the battery holder are provided in positions that are staggered when viewed from the axial direction of the cylindrical battery.

12. 2. The battery pack according to claim 1, wherein the battery holder is composed of a plurality of battery holder parts separated in an axial direction of the cylindrical battery accommodated in the battery holder.

13. The battery pack according to claim 12 , wherein the second groove is constituted by one of the battery holder parts and the other of the battery holder parts interconnected along the axial direction.

14. The battery pack of claim 12 , wherein a plurality of the battery holder parts are arranged in series.

15. The battery pack according to claim 1 , wherein the first groove and the second groove form a bent groove.

16. The battery pack of claim 1 , wherein the first groove and the second groove intersect.

17. The battery includes a plurality of cylindrical batteries, a heat absorbing member disposed between one cylindrical battery and the other cylindrical battery, and a battery holder that houses the plurality of cylindrical batteries and the heat absorbing member; the battery holder has a surrounding portion that fits around the outer periphery of the cylindrical batteries; a plurality of protrusions are provided on the inside surface of the surrounding portion of the battery holder; a first groove is provided extending along the axial direction of the cylindrical battery housed in the battery holder; and a second groove is provided extending along the circumferential direction of the cylindrical battery housed in the battery holder; the protrusion has a portion surrounded by the first groove and the second groove.

18. The battery pack according to claim 17 , wherein a portion of the first groove or the second groove extending in the longitudinal direction faces the protrusion.

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