Battery pack and method for manufacturing same

Abstract

The present invention makes it possible to fix a secondary battery cell to a battery holder at a high degree of reliability. A battery pack 100 comprises: a plurality of secondary battery cells 1 that each have a pair of cell end surfaces 1a and a cylindrical cell side surface 1c linking the cell end surfaces 1a to each other, one of the cell end surfaces 1a having exposed therefrom one from among a pair of cell electrodes; and a battery holder 2 that is provided with a holder body 10 having a plurality of body accommodation sections 14 respectively having one of the plurality of secondary battery cells 1 accommodated therein, and holder lid parts 20 each fixed to the holder body 10 with an adhesive layer 40 therebetween in a manner such that the secondary battery cells 1 are accommodated in the body accommodation sections 14 of the holder body 10. The holder lid parts 20 are each such that air vent holes 24 in communication with the upper surface of the holder lid part 20 are formed in a portion of a lid-side interface 23 which faces a body-side interface, of the holder body 10, where the body accommodation sections 14 are formed, and the adhesive layers 40 are respectively formed from the bonded interface between the holder lid part 20 and the holder body 10 so as to be continuous with a portion of the insides of the air vent holes 24.

Description

Battery Pack and Method for Manufacturing the Same 【0001】 The present disclosure relates to a battery pack and a method for manufacturing the same. 【0002】 A plurality of rechargeable secondary battery cells such as lithium-ion secondary battery cells are connected in series or in parallel to drive electric devices such as power tools or to drive electric moving bodies such as vehicles and construction machines. In such applications, battery packs are used (for example, Patent Document 1). Some of the secondary battery cells used in such battery packs are housed in battery holders. In addition, an adhesive is used to fix a cylindrical secondary battery cell held by the battery holder. 【0003】 However, when applying the adhesive, bubbles are generated, making it difficult to evenly distribute the fluid, resulting in uneven adhesive strength and individual differences. 【0004】 Japanese Patent Application Laid-Open No. 2018-6275 【0005】 One of the objects of one aspect of the present disclosure is to provide a battery pack and a method for manufacturing the same that can reliably fix a secondary battery cell to a battery holder. Another object of another aspect is to provide a battery pack and a method for manufacturing the same that make it difficult to generate bubbles when applying an adhesive material. Note that the description of these objects and problems of the present disclosure does not prevent the existence of other objects and problems. Also, one aspect of the present disclosure does not need to solve all of these problems. Furthermore, other problems can be extracted from the description of the specification, drawings, and claims of the present disclosure. 【0006】A battery pack according to one embodiment of the present disclosure comprises a battery holder comprising: a plurality of secondary battery cells, each having a pair of cell end faces and a cylindrical cell side surface connecting the cell end faces, with one of a pair of cell electrodes exposed on one of the cell end faces; a holder body having a plurality of main body storage sections for housing each of the plurality of secondary battery cells; and a holder lid portion fixed to the holder body via an adhesive layer when the secondary battery cells are housed in the main body storage sections of the holder body, wherein the holder lid portion has an air vent hole open in a part of the lid-side interface facing the main body-side interface of the holder body that forms the main body storage section, and the adhesive layer is formed continuously from the bonding interface between the holder lid portion and the holder body to a part of the interior of the air vent hole. 【0007】 Furthermore, a method for manufacturing a battery pack according to another embodiment of the present disclosure is a method for manufacturing a battery pack comprising: a battery holder comprising: a plurality of secondary battery cells, each having a pair of cell end faces and a cylindrical cell side connecting the cell end faces, with one of a pair of cell electrodes exposed on one of the cell end faces; a holder body having a plurality of main body storage sections for housing each of the plurality of secondary battery cells; and a holder lid that is fixed to the holder body via an adhesive layer when the secondary battery cells are housed in the main body storage sections of the holder body, the method comprising: a step of housing the plurality of secondary battery cells in the plurality of main body storage sections; and the holder The process includes: applying an uncured adhesive to a part of the main body side interface forming the main body storage portion of the main body; spreading the uncured adhesive at the end face of the lid compartment wall so that air bubbles generated in the uncured adhesive can escape from the battery holder to the outside through a plurality of air vents that open from a part of the lid side interface facing the main body side interface and communicate with the upper surface of the holder lid; and curing the uncured adhesive to form an adhesive layer that extends from the bonding interface between the holder lid and the holder body to a part inside the air vents, thereby bonding the holder lid and the holder body. 【0008】According to one embodiment of the present disclosure, in a structure in which the joint interface between the holder lid and the holder body is bonded with an adhesive, the situation in which air bubbles enter the uncured adhesive forming the adhesive layer and the adhesive strength becomes uneven can be prevented by releasing air from an air vent hole provided in the holder lid, thereby suppressing the generation of air bubbles and allowing the uncured adhesive to spread uniformly. 【0009】 This is a perspective view showing a battery pack according to an embodiment. This is a vertical cross-sectional view of the battery pack in Figure 1 along line II-II. This is an exploded perspective view of the battery pack in Figure 1. This is an exploded perspective view showing the assembled state of the battery pack in Figure 3. This is an exploded perspective view of the battery pack in Figure 4 viewed from diagonally below. This is an exploded cross-sectional view showing the holder cover being bonded to the holder body in Figure 4. This is a plan view showing the state of adhesive being applied to the upper surface of the holder body in Figure 4. This is an enlarged cross-sectional view of the main part showing the air vent hole in Figure 2. This is a horizontal cross-sectional view showing the adhesive being spread out in Figure 7. This is a horizontal cross-sectional view of Figures 2 and 8 along line X-X. This is a perspective view of a battery pack according to Comparative Example 1. This is an exploded perspective view showing the assembled state of the battery pack in Figure 11. This is a plan view showing the upper surface of the holder body in Figure 12. This is an exploded cross-sectional view showing the holder cover being bonded to the holder body in Figure 12. This is a cross-sectional view of the battery pack in Figure 11 along line XV-XV. This is an enlarged vertical cross-sectional view of the main part of the battery pack according to Comparative Example 2. This is an enlarged vertical cross-sectional view of the main part of the battery pack according to Embodiment 2. This is an enlarged vertical cross-sectional view of the main part of the battery pack according to Embodiment 3. This is an enlarged horizontal cross-sectional view of the main part of the battery pack according to Embodiment 4. 【0010】 The form of this disclosure may be specified by the following configurations and features. 【0011】 In other embodiments of the present disclosure, a battery pack is configured such that a portion of the adhesive layer is visible from the outside through the air vents. This configuration makes it possible to see from the outside that adhesive material has been applied to the back side of the holder cover. 【0012】Furthermore, in other embodiments of the present disclosure, the holder lid has a plurality of lid storage portions in a part of the lid-side interface, each housing a portion of the plurality of secondary battery cells, and the air vents are formed around the open ends of the lid storage portions on the lid-side interface. With this configuration, the holder lid can be positioned on the holder body by housing the ends of the secondary battery cells in the lid storage portions, and air bubbles can be removed from the adhesive by partially applying adhesive to the body-side interface and pressing it against the end face of the lid-side interface where the air vents are formed. 【0013】 Furthermore, in other embodiments of the present disclosure, the battery pack has an air vent opening in the narrowest region of the lid interface. With this configuration, when the uncured adhesive is partially applied to a wide area of ​​the main body interface and pressed and spread at the lid interface, the air is released from the air vent opening located between the partially applied adhesive regions, i.e., in the narrowest region of the lid interface, which is an area where air bubbles are likely to form due to the different adhesives being spread from different directions coming together. This effectively suppresses the generation of air bubbles and enables the formation of a uniform adhesive layer. 【0014】 Furthermore, in other embodiments of the present disclosure, the inner diameter of the air vent hole is one-third or less of the width of the narrowest region of the lid-side interface. This configuration allows for the maintenance of the strength of the lid-side interface while providing an air vent hole. 【0015】 Furthermore, in any of the above embodiments, the battery pack has a cross-sectional area of ​​the air vent hole that is larger than the cross-sectional area of ​​the gap between the side surface of the secondary battery cell and the inner surface of the main body housing. This configuration makes it easier to collect adhesive in the excess air vent hole, and has the advantage of preventing excessive adhesive from entering the gap between the side surface of the cell and the main body housing. 【0016】Furthermore, in other embodiments of the present disclosure, the main body side interface has an inclined surface at the end face of the main body housing that slopes downward toward the main body housing. With this configuration, adhesive can be accumulated in the inclined region, and a portion of the adhesive can be guided between the cell side of the secondary battery cell and the main body housing, thereby preventing the cylindrical secondary battery cell from rotating inside the main body housing by bonding the secondary battery cell to the holder body. 【0017】 Furthermore, in other embodiments of the present disclosure, a battery pack is configured such that, in any of the above embodiments, the holder body is closed at the top and bottom by the holder cover portion while the plurality of secondary battery cells are housed in the main body housing. This configuration makes it possible to close the cell end faces with the holder cover portion, thereby providing waterproofing and sealing for, for example, the cell electrodes provided on each cell end face. 【0018】 Furthermore, in other embodiments of the present disclosure, the battery pack in any of the above embodiments has the holder body having the body-side interfaces on its upper and lower surfaces to hold the upper and lower surfaces of each of the multiple secondary battery cells, while exposing the middle of each cell surface. With this configuration, the middle of the cell surfaces of the secondary battery cells held in the body housing are exposed, making it possible to air cool each secondary battery cell. 【0019】 Furthermore, in any of the above embodiments, a method for manufacturing a battery pack is provided in which the air vents are opened between the areas to which the uncured adhesive has been applied. This allows for the application of the uncured adhesive to a wide area of ​​the main body interface, and when it is pressed and spread at the lid interface, the air is released from the air vents located between the areas to which the adhesive has been applied, i.e., in the narrowest area of ​​the lid interface, which is an area where air bubbles are likely to form due to the different adhesives being spread from different directions. This suppresses the generation of air bubbles and allows the uncured adhesive to be distributed uniformly. 【0020】The embodiments of this disclosure will be described below with reference to the drawings. However, the embodiments shown below are examples for concretizing the technical concept of this disclosure, and this disclosure is not limited to the following. Furthermore, this specification does not limit the members shown in the claims to the members of the embodiments. In particular, the dimensions, materials, shapes, relative arrangements, etc. of the components described in the embodiments are not intended to limit the scope of this disclosure to those, unless otherwise specifically stated, but are merely illustrative examples. Note that the size and positional relationships of the members shown in each drawing may be exaggerated for clarity of explanation. Furthermore, in the following description, the same name and reference numeral indicate the same or similar members, and detailed explanations will be omitted as appropriate. Furthermore, each element constituting this disclosure may be configured such that multiple elements are made of the same member, with one member serving multiple elements, or conversely, the function of one member may be shared among multiple members. 【0021】 The battery pack disclosed herein can be used as a power source for portable electrical equipment such as power tools and electric cleaners, as a power source for mobile devices such as electric carts, electric scooters, and electric assist bicycles, or as a backup power source for servers, or as a battery pack for home, business, or factory use in stationary energy storage applications, and as a power source for vehicles such as hybrid cars and electric vehicles. Hereinafter, an embodiment of the present invention will be described, specifically a battery pack used as a power source for power tools used at construction sites, such as ground compaction machines. [Embodiment 1] 【0022】Figures 1 to 10 show a battery pack 100 according to Embodiment 1 of the present disclosure. In these figures, Figure 1 is a perspective view showing the battery pack 100 according to the embodiment, Figure 2 is a vertical cross-sectional view of the battery pack 100 in Figure 1 along line II-II, Figure 3 is an exploded perspective view of the battery pack 100 in Figure 1, Figure 4 is an exploded perspective view showing the assembled state of the battery pack 100 in Figure 3, Figure 5 is an exploded perspective view of the battery pack 100 in Figure 4 viewed from diagonally below, Figure 6 is an exploded cross-sectional view showing the holder cover portion 20 being bonded to the holder body 10 in Figure 4, Figure 7 is a plan view showing the state in which adhesive 42 has been applied to the upper surface of the holder body 10 in Figure 4, Figure 8 is an enlarged cross-sectional view of the main part showing the air vent hole 24 in Figure 2, Figure 9 is a horizontal cross-sectional view showing the adhesive 42 in Figure 7 being spread out, and Figure 10 shows a horizontal cross-sectional view along line X-X in Figures 2 and 8. The battery pack 100 shown in these figures comprises multiple secondary battery cells 1 and a battery holder 2. The battery pack 100 in Figure 1 has a box-like exterior, and houses multiple secondary battery cells 1 inside the battery holder 2. The electrodes of each secondary battery cell 1 are connected to lead plates. The lead plates are connected to a circuit board. Furthermore, the battery pack 100 can be housed in an outer case as needed, and the secondary battery cells 1 are discharged or charged via output terminals protruding from the surface of the outer case. (Secondary battery cell 1) 【0023】 The battery holder 2 holds multiple secondary battery cells 1. Each of the multiple secondary battery cells 1 has a pair of cell end faces 1a and a cell side surface 1c located between the cell end faces 1a. Each secondary battery cell 1 also has a pair of cell electrodes, i.e., a positive electrode and a negative electrode. One of the pair of cell electrodes is exposed on one of the pair of cell end faces 1a. In the examples shown in Figures 2 and 3, cylindrical secondary battery cells are used, each with a cylindrical outer casing. In the cylindrical secondary battery cell, each end face of the cylindrical cell side surface 1c serves as a cell end face 1a, and cell electrodes are provided on these surfaces. The cell electrodes are connected to lead plates (not shown) and connected in series or parallel with adjacent secondary battery cells 1. In the example shown in Figure 3, twelve secondary battery cells 1 are connected in 4 parallel × 3 series configurations. However, the number of secondary battery cells, the number of series connections, and the number of parallel connections are not limited to this example and are designed appropriately according to the required specifications. 【0024】 In the example shown in Figure 1, the outer casing is used with cylindrical secondary battery cells 1 arranged horizontally in a staggered pattern. The arrangement of the secondary battery cells is not limited to this example, and any arrangement can be used as appropriate. For example, cylindrical secondary battery cells may be arranged in a row or matrix. Such secondary battery cells 1 can be any known secondary battery, such as lithium-ion batteries, nickel-metal hydride batteries, or nickel-cadmium batteries. 【0025】 Each secondary battery cell 1 has a positive electrode and a negative electrode. The terminals of the positive or negative electrode are preferably located on one end face 1a of the secondary battery cell 1. In the example shown in Figure 3, the positive electrode terminal is located on one end face 1a of the secondary battery cell 1, and the other side of the outer casing serves as the negative electrode. (Battery holder 2) 【0026】 The battery holder 2 holds multiple secondary battery cells 1 in a position where the end faces 1a of each cell are on the same plane. In addition, the end faces 1a of adjacent secondary battery cells 1 are offset from each other, with the center of the circle shifted. 【0027】 The battery holder 2 is divided into a holder body 10 and a holder cover 20. In the example shown in the exploded perspective view of Figure 3, it is composed of three pieces, with the holder cover 20 fixed to the top and bottom of the holder body 10. With the secondary battery cell 1 inserted into the holder body 10, the battery holder 2 holds the secondary battery cell 1 by covering the ends of the secondary battery cell 1 that protrude from the top and bottom of the holder body 10 with the holder cover 20, as shown in Figure 2, etc. However, the battery holder may be divided into two or four or more parts, in addition to being divided into three parts. 【0028】 In this configuration, where the battery holder 2 is divided into multiple pieces, a fixing structure is required to secure each piece. Here, an adhesive layer 40 is formed at the bonding interface of each piece using adhesive material 42. The adhesive layer 40 is formed by curing the uncured adhesive material 42. (Holder body 10) 【0029】The holder body 10 has a box-like external shape with a top surface 11, a bottom surface 12, and side surfaces 13. Its interior is hollow, and it has multiple storage compartments 14, each housing a secondary battery cell 1. The top surface 11, bottom surface 12, and side surfaces 13 are each formed in a plate-like shape. As shown in the exploded perspective views of Figures 3 to 5, the storage compartments 14 are formed by openings in the box-shaped top surface 11 and bottom surface 12. The storage compartments 14 open along the outer shape of the secondary battery cell 1. If the secondary battery cell 1 is cylindrical, the storage compartment 14 is a slightly larger circle. By passing the secondary battery cell 1 through the storage compartments 14 on the top surface 11 and bottom surface 12, the upper and lower parts of the secondary battery cell 1 are held by the top surface 11 and bottom surface 12 of the holder body 10, respectively. The cell side surfaces 1c of the secondary battery cell 1 are exposed. Furthermore, by partially opening the side surface 13 of the holder body 10 and exposing the cell side surface 1c of the secondary battery cell 1, heat dissipation can be improved. 【0030】 As shown in Figures 2, 4, 6, and 7, when the secondary battery cells 1 are inserted into the holder body 10, the upper and lower parts of each secondary battery cell 1 protrude from the holder body 10. These upper and lower parts of the secondary battery cells 1 that protrude from the holder body 10 are held by the holder cover portion 20. The top surface 11 and the bottom surface 12 constitute the body-side interface at the joint interface between the holder body 10 and the holder cover portion 20, respectively. Furthermore, to facilitate the positioning of the holder cover portion 20, the holder body 10 has wall portions 15 protruding around the top surface 11 and the bottom surface 12, so that the holder cover portion 20 is positioned inside the area enclosed by the wall portions 15. The wall portions 15 are formed by extending the side surface 13 of the holder body 10. (Holder cover portion 20) 【0031】The holder cover portion 20 is fixed to the holder body 10 via an adhesive layer 40 when the secondary battery cell 1 is housed in the main body storage portion 14 of the holder body 10. The bottom surface 12 of the holder cover portion 20 constitutes the cover-side interface 23 at the bonding interface between the holder body 10 and the holder cover portion 20. Note that the adhesive material 42 or adhesive layer 40 is not shown in the exploded perspective view of Figure 3. As shown in Figures 2, 5, and 6, the holder cover portion 20 forms a cover storage portion 21 into which the upper and lower ends of the secondary battery cell 1 are inserted. The cover storage portion 21 is formed in a concave shape on the cover-side interface 23 where the holder cover portion 20 faces the holder body 10, or on the bottom surface 12 of the holder cover portion 20 in the example of Figure 5. The holder body 10 has openings in the top 11 and bottom 12 of the main body storage section 14, and a lid storage section 21 connected above and below it, forming a storage cylinder 3 that partially houses the upper and lower parts of the secondary battery cell 1. An opening window 22 is also formed in the bottom 12 of the lid storage section 21, exposing the cell ends of each secondary battery cell 1 housed in the battery holder 2. This makes it possible to connect the cell ends of the secondary battery cells 1 housed in the battery holder 2 to a lead plate or the like. 【0032】 The holder body 10 and holder cover 20 are made of a material with excellent insulating properties. Preferably, they are made of resin such as polycarbonate or PC-ABS alloy. (Air vent hole 24) 【0033】The portion of the lid-side interface 23 of the holder lid portion 20 that does not have a lid storage portion 21 faces the edge of the main body storage portion 14 of the holder body 10. The holder lid portion 20 has an air vent hole 24 in a part of this lid-side interface 23. As shown in the enlarged cross-sectional view of Figure 8, the air vent hole 24 is opened so as to penetrate the upper surface of the holder lid portion 20. Then, as shown in Figure 4, with the uncured adhesive 42 partially applied to the main body-side interface of the holder body 10, around the main body storage portion 14 into which the secondary battery cell 1 is inserted, the lid-side interface 23 of the holder lid is pressed against it as shown in Figures 5 and 6. As a result, the adhesive 42 is spread out from the state in Figure 7 to Figure 9, and as shown in Figure 10, the clumps of adhesive 42 connect with each other, and air bubbles are released to the outside through the air vent hole 24. As a result, the inclusion of air bubbles in the adhesive 42 can be reduced or avoided, and even when the adhesive 42 hardens and the adhesive layer 40 is formed, the inclusion of air layers can be avoided, and uniform bonding strength can be achieved. 【0034】 As mentioned above, in a configuration in which the battery holder is divided into multiple pieces, such as the holder body and the holder lid, a fixing structure is required to secure each piece. Examples of fixing structures include screw fastening, or fitting or press-fitting using pins or bosses. However, using these fixing structures requires forming screw holes or boss holes in the partition wall of the main body housing section that houses the secondary battery cells in the holder body, and fixing the holder lid, which results in a thicker partition wall. 【0035】 On the other hand, in recent years there has been a strong demand for miniaturization and weight reduction from the perspective of ease of carrying battery packs and improved fuel efficiency. Therefore, it is necessary to make the partitions thinner, making it difficult to make them thicker. Thus, it is conceivable to fix the partition joint interface with adhesive so that it can be secured even while keeping the partitions thin. Fixing with adhesive also provides waterproofing, and in addition to fixing the holder body and holder lid, it also fixes the secondary battery cells in the main body's storage compartment, thus preventing the secondary battery cells from rotating within the main body's storage compartment and damaging the joint with the lead plate. [Comparative Example 1] 【0036】For example, consider a battery pack 700 according to Comparative Example 1 shown in the perspective views of Figures 11 and 12, in which the holder body 710 and the holder cover 720 are fixed with adhesive 742. In this case, with the secondary battery cell 701 housed in the main body storage portion 714 of the holder body 710, partially uncured adhesive 742 is applied around the secondary battery cell 701 on the holder body 710 side, as shown in black in the plan view of Figure 13. Then, as shown in Figure 14, the holder cover 720 is closed, and the adhesive 742 is pushed and spread in the gap between the holder body 710 and the holder cover 720, thereby bonding and fixing the interface between the holder cover 720 and the holder body 710. 【0037】 However, in this configuration, the spread adhesive 742 was not uniform, and as shown in Figure 15, air bubbles BB sometimes formed in the adhesive layer 740 after the adhesive 742 cured. When the adhesive 742 is uneven around the secondary battery cell 701 in this way, it becomes impossible to exert a uniform bonding force, which could lead to a decrease in strength and reliability. 【0038】 Therefore, in the battery pack 100 according to this embodiment, as shown in Figures 2 and 8, an air vent hole 24 is opened in a part of the lid-side interface 23 of the holder lid 20, which is connected to the upper surface of the holder lid 20. This suppresses the generation of air bubbles, even if air bubbles are generated when the uncured adhesive 42 is spread at the bonding interface between the holder lid 20 and the holder body 10 during bonding. The air bubbles can be discharged to the outside from the battery holder 2 through the air vent hole 24. This prevents air bubbles from entering the uncured adhesive 42 at the bonding interface between the holder lid 20 and the holder body 10, which would form partial voids or air layers in the adhesive layer 40 and result in uneven bonding strength. By uniformly distributing the uncured adhesive 42, a homogeneous bonding layer is formed, improving the reliability of the bond. 【0039】 Furthermore, by providing an air vent hole 24 in the holder cover portion 20, a portion of the adhesive layer 40 can be seen from the outside through this air vent hole 24. This makes it possible to see from the outside that the adhesive 42 has been applied to the back side of the holder cover portion 20, which was not possible in the conventional method as shown in Figure 11. 【0040】 Furthermore, as shown in the enlarged cross-sectional view of Figure 8, when a portion of the adhesive 42 is pushed up into the air vent hole 24, the adhesive layer 40 is formed continuously from the bonding interface between the holder lid 20 and the holder body 10 to a portion of the inside of the air vent hole 24. This makes the adhesive layer 40 easier to see from the outside. [Embodiment 2] 【0041】 Furthermore, when fixing the holder body 10 and the holder lid 20 with adhesive 42, the secondary battery cell 1 can also be fixed to the battery holder 2 at the same time. In particular, when a cylindrical secondary battery cell is housed in the main body compartment, it is not possible to prevent the secondary battery cell from rotating in the circumferential direction due to vibration or shock, and there is a concern that the joint between the cell end face and the lead plate may break due to rotation. Therefore, by fixing the secondary battery cell 1 to the battery holder 2, the risk of such breakage can be reduced and reliability can be improved. [Comparative Example 2] 【0042】 However, if too much uncured adhesive is applied, as in the battery pack 800 of Comparative Example 2 shown in the vertical cross-sectional view of Figure 16, the adhesive 842 can drip down the cell side 801c, damaging the appearance and causing stickiness. Furthermore, if the adhesive 842 that has crept up from the gap between the holder cover 820 and the cell side 801c reaches the cell end face 801a, there is a concern that it may get between the cell electrode and the lead plate, hindering electrical connection or increasing contact resistance. On the other hand, if too little adhesive 842 is applied, the adhesive 842 cannot adequately reach the gap on the cell side 801c, resulting in insufficient fixation between the cell side 801c and the inner wall of the housing cylinder, making it impossible to prevent the rotation of the secondary battery cell 801. Therefore, there is a problem in controlling the amount of adhesive 842 applied and adjusting the dimensional error of the gap between the cell side 801c and the housing cylinder. 【0043】On the other hand, by opening the air vent hole 24 in the lid-side interface 23 of the holder lid portion 20, as shown in the vertical cross-sectional view of FIG. 17, the excess adhesive 42 can be guided to the air vent hole 24, and the advantage of reducing the problems caused by the excess adhesive 42 can be obtained. In particular, by making the cross-sectional area of the air vent hole 24 larger than the cross-sectional area of the gap between the cell side surface 1c of the secondary battery cell 1 and the inner surface of the storage cylinder, it becomes easier to collect the adhesive 42 in the excess air vent hole 24, and the advantage of suppressing the situation where the adhesive 42 excessively enters the gap between the cell side surface 1c and the storage cylinder can be obtained. 【0044】 Thus, not only is the gap at the bonding interface between the holder lid portion 20 and the holder main body 10 adhered with the adhesive 42, but the adhesive 42 is also spread into the gap between the main body storage portion 14 of the holder main body 10, the lid storage portion 21 of the holder lid portion 20, and the cell side surface 1c of the secondary battery cell 1. By fixing the cell side surface 1c to the inner wall of the storage cylinder of the battery holder 2, the cylindrical secondary battery cell 1 can be prevented from rotating within the storage cylinder, and the situation where the fixation of the lead plate to the cell end face 1a is broken due to the rotation of the secondary battery cell 1 can be avoided. [Embodiment 3] 【0045】 Furthermore, it is preferable that the main body side interface is provided with an inclined surface 18 having a downward gradient toward the main body storage portion 14 at the end face of the main body storage portion 14. With such a configuration, as shown in FIG. 18, the adhesive 42 is accumulated on the inclined surface 18, and a part of the adhesive 42 is guided between the cell side surface 1c of the secondary battery cell 1 and the main body storage portion 14. By adhering the secondary battery cell 1 to the holder main body 10, the cylindrical secondary battery cell 1 can be prevented from rotating inside the main body storage portion 14. 【0046】 In FIGS. 4 to 10 and the like, for the sake of explanation, the state of fixing the upper holder lid portion 20 inside the holder lid portion 20 to the holder main body 10 is shown. However, the same method can also be used when fixing the lower holder lid portion 20 to the holder main body 10. Hereinafter, the structure for fixing the upper holder lid portion 20 to the holder main body 10 will be mainly described. 【0047】In the example shown in Figure 5, the holder lid portion 20 has air vents 24 formed on the end face of the lid partition wall 25 that divides the lid storage portions 21 between themselves, around the open end of the lid storage portion 21 on the lid-side interface 23. The air vents 24 are also located on the body-side interface of the holder body 10, around the open end of the body storage portion 14, and face the end face of the body partition wall 16 that divides the body storage portions 14 between themselves. 【0048】Further, as shown in FIGS. 7 and 10, the air vent hole 24 is opened so as to be located between regions coated with the uncured adhesive 42. Here, the uncured adhesive 42 is in the end face of the main body partition wall 16 of the lid-side interface 23, in a region having a large area. In the example shown in FIG. 7, it is dot-coated in the region surrounded by the three cell end faces 1a of the secondary battery cell 1 arranged in a staggered or offset manner. The uncured adhesive 42 thus coated in dots is spread by the lid-side interface 23 of the holder lid portion 20, that is, the end face of the lid partition wall 25, as shown in the vertical cross-sectional view of FIG. 6, and stretched as indicated by the arrow in the horizontal cross-sectional view of FIG. 9, resulting in merging and mixing with the adjacent adhesive 42. At this time, bubbles are likely to occur. In particular, since the uncured adhesive 42 has a relatively high viscosity, it is easy to entrap air bubbles. Therefore, by arranging the air vent hole 24 in a region where such bubbles are likely to occur, even if bubbles occur, they can be easily discharged to the outside from the holder lid portion 20 through the air vent hole 24. That is, the air vent hole 24 is preferably arranged at the position farthest from each adhesive 42. In other words, it is preferable to arrange the air vent hole 24 in the middle between the applied adhesives 42. When applying the adhesive 42 between the three cell end faces 1a arranged in an offset manner as shown in FIG. 7, it is preferable to provide the air vent hole 24 at the position where two cell end faces 1a are adjacent. In other words, the air vent hole 24 is opened in the narrowest region of the lid partition wall 25 of the lid-side interface 23. By adopting such an arrangement, when the uncured adhesive 42 is applied to a wide region of the main body-side interface and pressed and spread at the lid-side interface 23, the different adhesives 42 spread from different directions are combined, and air is removed from the air vent hole 24 provided in the region between the regions coated with the adhesive 42, which is a region where bubbles are likely to occur, that is, in the narrowest region of the lid-side interface 23, thereby suppressing the generation of bubbles and allowing the uncured adhesive 42 to spread evenly. 【0049】Furthermore, it is preferable that the inner diameter of the air vent hole 24 be 1 / 3 or less of the width of the narrowest region of the lid partition wall 25 of the lid side interface 23. This makes it possible to maintain the strength of the lid partition wall 25 of the lid side interface 23 while providing the air vent hole 24. [Embodiment 4] Furthermore, the air vent hole is not limited to a configuration that penetrates the lid partition wall, but may be formed in the shape of a slit. For example, in the battery pack 400 according to Embodiment 4 shown in Figure 19, a slit provided in the shape of a groove on the surface of the lid partition wall 25D is made to penetrate the front surface of the holder lid portion 20D to form the air vent hole 24D. With this configuration, it is not necessary to provide a through hole in the thinnest part of the lid partition wall 25D, which has the advantage of being easy to mold and easy to achieve strength. With this configuration, it is also possible to easily supply adhesive to the gap between the cell side surface 1c of the secondary battery cell 1 and the lid storage portion 21, which has the advantage of being easy to form the adhesive layer 40. In the example shown in Figure 19, a slit-shaped air vent hole 24D is formed in each adjacent lid storage section 21D, offset to the area where the lid storage sections 21D are closest. However, it may also be formed in only one of the lid storage sections 21D. (Adhesive 42) 【0050】 The adhesive 42 is selected from materials that exhibit adhesive strength according to the material of the holder body 10 and the holder cover 20. Preferably, synthetic adhesives such as acrylic, epoxy, silicone, and polyurethane can be used. [Battery pack manufacturing method] 【0051】 The manufacturing method of the battery pack described above, particularly the method of fixing the battery holder 2, will now be explained. First, a holder body 10 and a holder cover 20 are prepared as the battery holder 2. The holder body 10 has multiple body storage sections 14, each housing a plurality of secondary battery cells 1. The holder cover 20 is a component for closing the holder body 10 when the secondary battery cells 1 are housed in the body storage sections 14 of the holder body 10. The holder cover 20 also has a plurality of air vents 24 that open from a part of the cover-side interface 23 facing the body-side interface and communicate with the upper surface of the holder cover 20. 【0052】Next, multiple secondary battery cells 1 are housed in multiple main body storage sections 14 of the holder body 10. Each secondary battery cell 1 has a pair of cell end faces 1a and a cylindrical cell side surface 1c connecting these cell end faces 1a. One of the pair of cell electrodes is exposed on one of the cell end faces 1a. 【0053】 Furthermore, an uncured adhesive 42 is applied to a part of the main body side interface that forms the main body storage portion 14 of the holder body 10. 【0054】 Then, with the air bubbles generated in the uncured adhesive 42 being released from the battery holder 2 to the outside through the air vent holes 24 of the holder cover portion 20, the uncured adhesive 42 is spread out at the end face of the cover compartment wall 25. 【0055】 Finally, the uncured adhesive 42 is cured to form an adhesive layer 40 that extends from the bonding interface between the holder cover 20 and the holder body 10 to a portion of the inside of the air vent hole 24, thereby bonding the holder cover 20 and the holder body 10. In this structure, where the bonding interface between the holder cover 20 and the holder body 10 is bonded with adhesive 42, the uncured adhesive 42 forming the adhesive layer 40 may become trapped in the uncured adhesive 42, resulting in uneven adhesion. However, by releasing air through the air vent hole 24 provided in the holder cover 20, the generation of air bubbles is suppressed, and the uncured adhesive 42 can be spread uniformly. 【0056】 In the above example, the battery pack is attached to the electrical device to be powered, and power is supplied to the electrical device. When the remaining capacity of the battery pack becomes low or the battery pack deteriorates over time, the battery pack can be replaced, allowing the electrical device to continue to be used. However, the present invention is not limited to replaceable battery packs that mainly house secondary battery cells, but can also be applied to configurations in which secondary battery cells are housed within the casing of the electrical device. In this disclosure, a battery pack is defined as a device in which secondary battery cells are housed within a case, and also includes devices in which the secondary battery cells for driving are built into the casing of the electrical device itself. In other words, the present invention is not limited to replaceable battery packs, but can also be applied to electrical devices that have built-in secondary battery cells. 【0057】The battery pack and its manufacturing method described herein can be suitably used as a power source for construction machinery such as ground compaction machines, power tools, wireless devices, electric cleaners, and other portable electrical equipment. It can also be appropriately used as a power source for electric assist bicycles, self-propelled delivery robots, electric carts for delivery and golf courses, electric scooters, construction machinery, hybrid vehicles, and electric vehicles. Alternatively, it can be used for stationary energy storage devices, such as battery packs for homes, businesses, and factories, or as backup power sources for servers. 【0058】 100, 400...Battery pack 1...Secondary battery cell; 1a...Cell end face; 1c...Cell side 2...Battery holder 3...Storage cylinder 10...Holder body 11...Top surface 12...Bottom surface 13...Side 14...Main body storage section 15...Wall section 16...Main body compartment wall 18...Inclined surface 20, 20D...Holder lid section 21...Lid storage section 22...Opening window 23...Lid side interface 24, 24D...Air vent hole 25, 25D...Lid compartment wall 40...Adhesive layer 42...Uncured adhesive 700...Battery pack 701...Secondary battery cell 702...Battery holder 710...Holder body 714...Main body storage section 720...Holder lid section 740...Adhesive layer 742...Adhesive 800...Battery pack 801...Secondary battery cell; 801a...Cell end face; 801c...Cell side; 820...Holder cover; 842...Adhesive; BB...Air bubble

Claims

1. A battery holder comprising: a battery pack comprising: a plurality of secondary battery cells, each having a pair of cell end faces and a cylindrical cell side connecting the cell end faces, with one of a pair of cell electrodes exposed on one of the cell end faces; a holder body having a plurality of main body storage sections for housing each of the plurality of secondary battery cells; and a holder lid portion fixed to the holder body via an adhesive layer when the secondary battery cells are housed in the main body storage sections of the holder body; wherein the holder lid portion has an air vent hole opening in a part of the lid-side interface facing the main body-side interface of the holder body that forms the main body storage section, and the adhesive layer is formed continuously from the bonding interface between the holder lid portion and the holder body to a part of the inside of the air vent hole.

2. A battery pack according to claim 1, wherein a portion of the adhesive layer is visible from the outside through the air vent hole.

3. A battery pack according to claim 1, wherein the holder lid portion has a plurality of lid storage portions in a part of the lid-side interface, each housing a part of the plurality of secondary battery cells, and the air vents are formed around the open ends of the lid storage portions on the lid-side interface.

4. A battery pack according to claim 1, wherein the air vent hole is opened in the narrowest region of the lid-side interface.

5. A battery pack according to claim 1, wherein the inner diameter of the air vent hole is 1 / 3 or less of the width of the narrowest region of the lid-side interface.

6. A battery pack according to any one of claims 1 to 5, wherein the cross-sectional area of ​​the air vent hole is larger than the cross-sectional area of ​​the gap between the side surface of the secondary battery cell and the inner surface of the main body housing.

7. A battery pack according to any one of claims 1 to 5, wherein the main body side interface is provided with an inclined surface at the end face of the main body storage portion that slopes downward toward the main body storage portion.

8. A battery pack according to any one of claims 1 to 5, wherein the plurality of secondary battery cells are housed in the main body storage section, and the top and bottom of the holder body are closed by the holder lid section.

9. A battery pack according to claim 8, wherein the holder body has body-side interfaces on its upper and lower surfaces to hold the upper and lower surfaces of each of the plurality of secondary battery cells, and exposes the middle of each of the cell surfaces.

10. A battery holder comprising: a battery pack manufacturing method comprising: a battery holder comprising: a battery holder comprising: a step of storing the plurality of secondary battery cells in the plurality of body storage sections; a step of applying an uncured adhesive to a part of the body side interface of the holder body that forms the body storage section; and a step of spreading the uncured adhesive at the end surface of the lid section wall of the holder lid, so that air bubbles generated in the uncured adhesive can escape from the battery holder to the outside through a plurality of air vents that open from a part of the lid side interface facing the body side interface and communicate with the upper surface of the holder lid, A method for manufacturing a battery pack, comprising the step of curing the uncured adhesive to form an adhesive layer that extends from the bonding interface between the holder cover and the holder body to a part of the inside of the air vent hole, thereby bonding the holder cover and the holder body.

11. A method for manufacturing a battery pack according to claim 10, wherein the air vents are opened between regions to which the uncured adhesive has been applied.

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