Battery pack, battery module, battery pack, and method for manufacturing battery pack

Abstract

The present invention provides a battery pack in which unit cells can be easily and securely fixed. The present invention pertains to a battery pack 100a comprising: a plurality of unit cells 10; a holder 20 having a plurality of retaining holes 20a for storing the unit cells 10; and an adhesive (ad) for bonding the unit cells 10 and the retaining holes 20a, respectively. The holder 20 has a plurality of adhesive filling parts 20b on the inside thereof, and at least some of the plurality of retaining holes 20a communicate with two or more of the adhesive filling parts 20b.

Description

Battery assembly, battery module, battery pack, and method of manufacturing battery assembly

[0001] The present invention relates to a battery assembly, a battery module, a battery pack, and a method for manufacturing a battery assembly.

[0002] To achieve higher output and capacity, battery packs made up of a combination of multiple cells are used. For example, Patent Document 1 discloses a battery pack including multiple cells and a holder with multiple retaining holes for accommodating the cells. Such battery packs are manufactured by inserting cells into each retaining hole and then injecting adhesive into the retaining holes. The adhesive injected into the retaining holes fills the gaps between the retaining holes and the cells, securing the cells in place.

[0003] Patent Document 2 discloses a battery pack in which a rubber holder located between a first holder and a second holder is sandwiched between the first holder and the second holder on both sides, causing the rubber holder to elastically deform and press against the surface of the cylindrical unit cells, thereby fixing the unit cells.

[0004] JP 2019-008887 A JP 2019-216054 A

[0005] In the battery pack of Patent Document 1, the adhesive must be reliably filled in the gap between the cell and the retaining hole; if it is not filled, the cell may not be sufficiently fixed.

[0006] The battery pack of Patent Document 2 does not use an adhesive, and therefore the fixing strength may be insufficient in applications that are subject to vibration, such as in automobiles.

[0007] In view of the above, an object of the present invention is to provide a battery assembly, a battery module, a battery pack, and a method for manufacturing a battery assembly, which are capable of easily and reliably fixing unit cells.

[0008] One aspect of the present invention relates to an assembled battery comprising a plurality of single cells, a holder having a plurality of retaining holes for accommodating the single cells, and an adhesive for bonding the single cells to the retaining holes, wherein the holder has a plurality of adhesive-filled portions therein, and at least some of the plurality of retaining holes are in communication with two or more of the adhesive-filled portions.

[0009] According to the present invention, it is possible to provide a battery assembly, a battery module, a battery pack, and a method for manufacturing a battery assembly, in which unit cells can be easily and reliably fixed.

[0010] FIG. 1 shows an exploded perspective view of one embodiment of a battery pack including multiple battery modules. FIG. 2A shows an exploded perspective view of one embodiment of a battery module. FIG. 2B shows a perspective view of the exterior of the battery module of FIG. 2A. FIG. 3A shows an exploded perspective view of one embodiment of a battery assembly. FIG. 3B shows a perspective view of the upper holder of the battery assembly of FIG. 3A turned upside down from the state shown in FIG. 3A and an enlarged view of the convex portion of the adhesive-filled portion. FIG. 3C shows a perspective view of the lower holder of the battery assembly of FIG. 3A and an enlarged view of the concave portion of the adhesive-filled portion. FIG. 3D shows an enlarged view of a portion of the battery assembly of FIG. 3A, with the lower holder of the battery assembly of FIG. 3A shown as transparent. FIG. 3E shows another embodiment of the convex portion and concave portion constituting the adhesive-filled portion. FIG. 4 shows a conceptual diagram of a process for bonding a battery cell, an upper holder, and a lower holder with an adhesive. FIG. 5 conceptually illustrates the tapered shape of the retaining hole. FIG. 6A shows an enlarged perspective view of the upper and lower holders used in another embodiment of the battery pack. FIG. 6B shows a cross-sectional view of the holders shown in FIG. 6A. FIG. 7 shows a perspective view of the battery module of the embodiment of FIG. 2A with the flexible substrate, cell monitoring device, and cooling fan removed. FIG. 8 shows a perspective view of the battery module of the embodiment of FIG. 2A with the flexible substrate, cell monitoring device, and cooling fan attached. FIG. 9 shows the connection between the upper tab busbar and the upper FPC and the connection between the cell and the upper tab busbar of the battery module of the embodiment of FIG. 2A. FIG. 10 shows an enlarged view of the connection between the cell and the upper tab busbar of the battery module of the embodiment of FIG. 2A. FIG. 11 shows an example of the connection between the cell and the upper tab busbar. FIG. 12 shows the structure of the back side of the main busbar of the battery module of the embodiment of FIG. 2A. FIG. 13 shows a conceptual diagram of a structure for cooling the cell in the battery module with a cooling fan. FIG. 14 shows a conceptual cross-sectional view of a structure for cooling the cells in a battery module with a cooling fan.

[0011] The present invention will be specifically described using the following embodiments as examples, but the present invention is not limited thereto. Unless a specific description is given of each device, mechanism, means, etc. in this specification, those skilled in the art can use mechanical devices, mechanisms, means, etc. that are well known to those skilled in the art. Each embodiment can be combined based on the ordinary knowledge of those skilled in the art, and configurations not specifically described in each embodiment can have the same configuration as other embodiments or a configuration appropriate for that embodiment.

[0012] In this specification, the upper portion refers to the positive z direction in Fig. 2A, the upper surface refers to the surface on the positive z direction side, the lower portion refers to the negative z direction in Fig. 2A, the lower surface refers to the surface on the negative z direction side, and the thickness direction refers to the z direction.

[0013] FIG. 1 shows a perspective exploded view of one embodiment of a battery pack 1000 including a plurality of battery modules 100 .

[0014] The battery pack 1000 includes six battery modules 100, five battery module bus bars 200 that electrically connect in parallel the same poles of the electrodes (external connection portions) on one side of the battery modules 100 between the battery modules 100, a control device 301, connectors 302, a frame 400, and six exterior panels 501 to 506. The control device 301 may include a battery management system and may perform temperature control and power input / output management for the battery pack 1000. The connectors 302 may include an output connector portion and may also include various meters and the like. Although not shown, the battery pack 1000 also includes five battery module bus bars that electrically connect in parallel the same poles of the electrodes (external connection portions) on the other side of the battery modules 100 in FIG. 1 . The battery pack 1000 can also be configured such that the six battery modules 100 are electrically connected in series by the battery module bus bar 200 by arranging the poles of the six battery modules 100 alternately.

[0015] FIG. 2A shows an exploded perspective view of one embodiment of the battery module 100. FIG. 2B shows a perspective view of the exterior of the battery module 100 of FIG. 2A. FIG. 3A shows an exploded perspective view of one embodiment of a battery assembly 100a built into the battery module 100. FIG. 3B shows a perspective view of the upper holder 21 of the battery assembly 100a of FIG. 3A turned upside down from the state shown in FIG. 3A and an enlarged view of the protruding portion 21b of the adhesive-filled portion. FIG. 3C shows a perspective view of the lower holder 22 of the battery assembly 100a of FIG. 3A and an enlarged view of the recessed portion 22b of the adhesive-filled portion. FIG. 3D shows an enlarged view of a portion of the battery assembly 100a in which the lower holder 22 of the battery assembly 100a of FIG. 3A is transparent.

[0016] As shown in Figures 2A and 2B, this battery module 100 includes a plurality of cells 10, a holder 20 that secures and houses the cells 10, a tub bus bar 30 that extracts current from the cells 10, a general bus bar 40 that connects to the tub bus bar 30 and serves as an electrode to the outside, a flexible printed circuit (FPC) 50 that connects to the tub bus bar 30, a cell monitoring unit (CMU) 53 that connects to the FPC 50 and monitors the voltage of the tub bus bar 30, a cooling fan 60, a bracket 70 for securing the battery module 100 to a frame 400 or the like of the battery pack 1000, a housing 80, and a cable 90 that connects the cooling fan 60 to a control device 301.

[0017] Here, holder 20 consists of upper holder 21 and lower holder 22; tab busbar 30 consists of upper tab busbar 31, lower tab busbar 32, first end tab busbar 33, and second end tab busbar 34; total busbar 40 consists of first total busbar 41 and second total busbar 42; FPC 50 consists of upper FPC 51 and lower FPC 52; cooling fan 60 consists of upper cooling fan 61 and lower cooling fan 62; bracket 70 consists of first bracket 71 and second bracket 72; and housing 80 consists of upper housing 81 and lower housing 82.

[0018] 3A , in this embodiment, the battery pack 100a includes a plurality of cells 10, an upper holder 21 having a plurality of upper retaining holes 21a that accommodate the cells 10, and a lower holder 22 having a plurality of lower retaining holes 22a that accommodate the cells 10. The upper retaining holes 21a and the lower retaining holes 22a form retaining holes 20a. Although not shown, the battery pack 100a further includes an adhesive ad that adheres the cells 10, the upper retaining holes 21a of the upper holder 21, and the lower retaining holes 22a of the lower holder 22 together.

[0019] As shown in Fig. 3B, the upper holder 21 has an upper holding hole 21a and a plurality of protrusions 21b formed adjacent to the upper holding hole 21a on its lower surface 21e. As shown in Fig. 3C, the lower holder 22 has a lower holding hole 22a and a plurality of recesses 22b formed adjacent to the lower holding hole 22a on its upper surface 22d. As shown in Fig. 3D, the protrusions 21b of the upper holder 21 and the recesses 22b of the lower holder 22 can form the adhesive filling portion 20b.

[0020] <Single Cell> As long as the advantageous effects of the present invention are obtained, the single cell 10 may be formed in a rectangular prism shape and may have a pair of electrodes at one axial end. However, as in the illustrated embodiment, the single cell 10 is preferably formed in a cylindrical shape and configured to have electrodes at both axial ends. Furthermore, while the illustrated embodiment shows an example in which a lithium-ion secondary battery is used, this is not limiting. For example, the single cell 10 may be an 18650 battery, a 21700 battery, or the like.

[0021] In this embodiment, 16 cells 10 are arranged in the x direction with the positive and negative electrodes oriented in the same direction, and 12 cells are arranged in the y direction with the positive and negative electrodes oriented alternately. The battery pack 100a has 16 cells 10 connected in parallel and 12 cells 10 connected in series.

[0022] In this embodiment, the battery pack 100a includes a total of 192 cells 10, but the number of cells 10 may be 50 or more, 100 or more, or 150 or more, or 500 or less, 300 or less, or 200 or less. The battery pack 100a may also include 5 or more, 10 or more, or 20 or more cells 10 connected in parallel, and 50 or less, 30 or less, or 20 or less cells 10 connected in parallel or in series.

[0023] <Holder> The holder 20 may be configured as a single structure or as three or more structures as long as the advantageous effects of the present invention are obtained, but as in the illustrated embodiment, the holder 20 is preferably divided into an upper holder 21 and a lower holder 22. In the illustrated embodiment, the upper holder 21 and the lower holder 22 are formed from resin.

[0024] The holder 20 has a plurality of adhesive filling sections 20b inside. Here, "inside" means being located midway in the thickness direction, that is, even if the adhesive filling sections 20b are connected to the top and / or bottom surfaces of the holder 20 through holes or the like, they are not directly present on the top and / or bottom surfaces.

[0025] The multiple adhesive filling sections 20b of the holder 20 are the places where the adhesive is filled, and because they are connected to the holding holes 20a for the single cells 10, the adhesive is filled not only in the adhesive filling sections 20b but also in the holding holes 20a, thereby fixing the single cells 10 to the holder 20.

[0026] The adhesive filling portion 20b is located between the lower surface 21e of the upper holder 21 and the upper surface 22d of the lower holder 22. This location makes it possible to easily form the adhesive filling portion 20b and to easily place and fill the adhesive during the adhesive filling operation. In this case, the upper holder 21 and the lower holder 22 can be assembled after the adhesive has been placed in the adhesive filling portion 20b.

[0027] The adhesive filling portion 20b can be positioned between the recessed and protruding portions formed on the lower surface 21e of the upper holder 21 and the upper surface 22d of the lower holder 22. In the illustrated embodiment, the adhesive filling portion 20b is positioned between the protruding portion 21b of the upper holder 21 and the recessed portion 22b of the lower holder 22. When the upper holder 21 and the lower holder 22 are combined, the adhesive ad is present between the protruding portion 21b and the recessed portion 22b, bonding them together.

[0028] The shapes of the recessed portion 22b and the protruding portion 21b of the upper holder 21 and the lower holder 22 are not particularly limited, but are preferably conical as shown in the figure. If the recessed portion and the protruding portion have conical shapes that allow them to fit together, even if the upper holder 21 and the lower holder 22 are fitted together at slightly different positions, the conical slope of the recessed portion and the conical slope of the protruding portion slide against each other, ensuring reliable alignment at the intended position. As a result, fitting the upper holder 21 and the lower holder 22 together can be made very easy. Furthermore, as described below, adhesive placed in the recessed portion 22b can be smoothly pushed out by the protruding portion 21b. Here, the conical shape does not have to be a perfect cone as long as it can provide such advantageous effects, and can include, for example, a hemispherical shape with a rounded tip.

[0029] In addition, in the illustrated embodiment, an example is shown in which the recess and protrusion are conical in shape, but as shown in FIG. 3E, they may also be configured with recess 22b' and protrusion 21b' formed in a stepped cylindrical shape that can fit together.

[0030] In this embodiment, when adhesive filling portions 20b are formed at positions other than the ends in the x and y directions of the holder 20, one adhesive filling portion 20b communicates with three adjacent retaining holes 20a. When adhesive filling portions 20b are formed at the ends in the x and y directions of the holder 20, one adhesive filling portion 20b communicates with one or two retaining holes 20a. Furthermore, one retaining hole 20a located at a position other than the ends in the x and y directions of the holder 20 communicates with three adjacent adhesive filling portions 20b, and one retaining hole 20a located at the ends in the x and y directions of the holder 20 communicates with one or two adhesive filling portions 20b.

[0031] However, it is preferable that one retaining hole 20a communicates with two or more adhesive filling sections 20b, because the gap between the cell 10 and the retaining hole 20a is filled with adhesive from two or more adhesive filling sections 20b, thereby reliably adhering and fixing the cell 10. On the other hand, it is preferable that one adhesive filling section 20b communicates with two or more retaining holes 20a, because this makes it very easy to fill the gap between the cell 10 and the retaining hole 20a with adhesive.

[0032] In this embodiment, because the cells 10 are arranged in a staggered pattern in the x and y directions, the adhesive filling portion 20 b is located at the center of three adjacent retaining holes 20 a, and one adhesive filling portion 20 b communicates with three retaining holes 20 a, and one retaining hole 20 a communicates with three adhesive filling portions 20 b. Also, for example, if the cells 10 are arranged in a lattice pattern in the x and y directions, one adhesive filling portion 20 b can communicate with two or four retaining holes 20 a, and one retaining hole 20 a can communicate with two or four adhesive filling portions 20 b.

[0033] 3D , the holder 20 preferably holds the cell 10 at an approximately midpoint in the axial direction (z direction) of the cell 10. Here, the approximately midpoint means that the deviation between the center position of the cell 10 in the axial direction and the center position of the holder 20 in the thickness direction is within 20%, 10%, or 5% of the length of the cell 10 in the axial direction.

[0034] With this configuration, the positive and negative electrodes of the cells 10 can be positioned in the spaces separated above and below by the holder 20. This allows the cooling fan 60 to efficiently cool the electrodes of the cells 10 when the battery module 100 is constructed, as will be described later. Furthermore, by holding the cells 10 at approximately their middle positions with the holder 20, the vicinity of the center of gravity of the cells 10 is fixed, resulting in a structure that is resistant to vibration.

[0035] 3A to 3D, the adhesive ad is placed in the recessed portion 22b, and then the upper holder 21 and the lower holder 22 are assembled together. As a result, the adhesive ad is pushed out by the protruding portion 21b into the gaps between the upper wall surface 21c of the upper holding hole 21a and the lower wall surface 22c of the lower holding hole 22a and the unit cell 10. The pushed-out adhesive ad then adhesively fixes the unit cell 10, the upper holder 21, and the lower holder 22.

[0036] In this embodiment, it is very easy to apply adhesive to the adhesive filling portion 20b. Furthermore, even if the viscosity of the adhesive used is relatively high, the adhesive ad applied to the recessed portion 22b can be pushed out by the protruding portion 21b, thereby sufficiently filling the gaps between the upper wall surface 21c, the lower wall surface 22c, and the cells 10. Furthermore, since the adhesive ad can be applied to the adhesive filling portion 20b with the recessed portion 22b exposed before combining the upper holder 21 with the lower holder 22, a consistent amount of adhesive ad can be applied. Furthermore, combining the upper holder 21 and the lower holder 22 allows the adhesive ad to be pushed out all at once from the multiple adhesive filling portions 20b into the gaps between the multiple cells 10 and the multiple holding holes 20a that accommodate the cells, thereby allowing multiple cells 10 to be bonded and fixed at one time.

[0037] Figure 4 shows a conceptual diagram of the process of bonding the cell 10, upper holder 21, and lower holder 22 with adhesive ad. Figure 4(a) shows the first cell 11 and second cell 12, the recess 22b of the lower holder 22, and the lower wall surface 22c of the lower holding hole 22a of the lower holder 22. Figure 4(b) shows the state in which adhesive ad has been placed in the recess 22b of Figure 4(a). Figures 4(c) and (d) show the state in which the upper holder 21 is moved from top to bottom, and in this way, the protrusion 21b of the upper holder 21 is mated with the recess 22b of the lower holder 22 on which adhesive ad has been placed. 4(e), when the convex portion 21b of the upper holder 21 is fitted into the concave portion 22b of the lower holder 22, the adhesive ad arranged in the concave portion 22b is pushed out by the fitting of the concave portion 22b and the convex portion 21b, and flows into the gaps provided among the upper wall surface 21c of the upper holder 21, the lower wall surface 22c of the lower holder 22, the first cell 11, and the second cell 12, thereby adhesively fixing them together. Here, because the concave portion 22b and the convex portion 21b have a conical shape, the adhesive ad arranged in the concave portion 22b can be smoothly pushed out by the convex portion 21b.

[0038] The upper holding hole 21a of the upper holder 21 has a tapered upper wall surface 21c whose diameter increases from the upper surface 21d to the lower surface 21e. The lower holding hole 22a of the lower holder 22 has a tapered lower wall surface 22c whose diameter increases from the lower surface 22e to the upper surface 22d. Figure 5 conceptually illustrates the tapered shapes of the upper holding hole 21a and the lower holding hole 22a. By configuring the upper wall surface 21c of the upper retaining hole 21a and the lower wall surface 22c of the lower retaining hole 22a in this manner, the gaps formed between the single battery 10 and the upper wall surface 21c and lower wall surface 22c are wider on the lower surface 21e side of the upper holder 21 and the upper surface 22d side of the lower holder 22 than on the upper surface 21d side of the upper holder 21 and the lower surface 21e side of the lower holder 22, allowing adhesive to be filled sufficiently and smoothly from the adhesive filling section 20b into the gaps formed on the outer periphery of the single battery 10, ensuring reliable adhesive fixation of the single battery 10.

[0039] Because the holder 20 is divided into the upper holder 21 and the lower holder 22, the tapered shape of the upper wall surface 21c and the lower wall surface 22c of the holding holes 21a, 22a can be easily formed using a resin molding mold. For example, this tapered shape can be the same as the shape of the removal taper when the resin upper holder 21 and lower holder 22 are removed from the mold.

[0040] Figures 6A and 6B disclose upper and lower holders 21 and 22 that have a different configuration of adhesive filling section 20b from the embodiment of Figures 3A to 3D. Figure 6A shows an enlarged perspective view of the upper and lower holders, and Figure 6B shows a cross-sectional view of the holders of Figure 6A.

[0041] 3A to 3D, the adhesive filling portion 20b does not communicate with the upper surface 21d of the upper holder 21 and the lower surface 22e of the lower holder 22. On the other hand, in the embodiment shown in Figures 6A and 6B, the upper surface 21d of the upper holder 21 has an adhesive injection hole 21f that communicates with the adhesive filling portion 20b.

[0042] 6A and 6B , as in the embodiment of Figures 3A to 3D , one adhesive filling section 20b communicates with three adjacent retaining holes 20a, and one retaining hole 20a communicates with three adjacent adhesive filling sections 20b. By injecting adhesive from adhesive injection holes 21f into the adhesive filling sections 20b, the gaps between the three unit cells 10 and the retaining holes 20a are filled with adhesive, thereby adhesively fixing the unit cells 10. Also, adhesive is injected from the three adhesive filling sections 20b into the gaps between one unit cell 10 and the retaining holes 20a.

[0043] When manufacturing the battery pack 100a using the holder of this embodiment, the upper holder 21 and the lower holder 22 are combined with a plurality of cells 10 accommodated in the holding holes 20a, and adhesive is injected through the adhesive injection holes 21f. The injected adhesive is then forced to flow out into the gaps between the cells 10 and the holding holes 20a, through which the adhesive filling portions 20d communicate, by the injection pressure, thereby adhering and fixing the cells 10, thereby manufacturing the battery pack 100a.

[0044] <Bus Bars> The battery module 100 has bus bars 30, 40 that electrically connect the electrodes of the cells 10. The battery module 100 can use the bus bars 30, 40 to extract power from the cells 10 and supply the power to the outside, and / or can supply power from the outside to charge the cells 10. The bus bars 30, 40 can be configured from a tub bus bar 30 that extracts power from the cells 10, and a total bus bar 40 that supplies the power collected by the tub bus bar 30 to the outside.

[0045] FIG. 7 is a perspective view of the battery module 100 of the above embodiment with the upper FPC 51, lower FPC 52, CMU 53, upper cooling fan 61, lower cooling fan 62, and housing 80 removed.

[0046] In this embodiment, the bus bars 30, 40 are composed of an upper tab bus bar 31 that connects the electrodes on the upper side of the multiple single cells 10, a lower tab bus bar 32 that connects the electrodes on the lower side of the multiple single cells 10, a first end tab bus bar 33 and a second end tab bus bar 34 at both ends of the upper part, and a first general bus bar 41 and a second general bus bar 42 that have electrodes (external connection parts) 41c, 42c that are electrically connected to the first and second end tab bus bars 33, 34, respectively, and are used to supply power to the outside.

[0047] In this embodiment, each upper tub bus bar 31 and lower tub bus bar 32 connects 16 cells 10 in parallel in the x direction, and each upper tub bus bar 31 and lower tub bus bar 32 connects two rows of cells in series in the y direction.

[0048] The upper tub bus bar 31 and the lower tub bus bar 32 connect the columns of the cells 10 in the y direction so that the poles alternate. For example, if the fifth and sixth columns of the twelve columns of cells 10 arranged in the y direction are connected to the upper tub bus bar 31, the lower tub bus bar 32 connects the sixth and seventh columns of the cells 10 in the y direction. The upper tub bus bar 31 adjacent to the upper tub bus bar 31 connecting the fifth and sixth columns connects the seventh and eighth columns of the cells 10. In this way, the twelve columns of the cells 10 arranged in the y direction are connected in series. The cells 10 are charged by extracting power from the external connection parts 41c, 42c of the first and second general bus bars 41, 42 through the first and second end tub bus bars 33, 34, and by receiving power from the external connection parts 41c, 42c of the first and second general bus bars 41, 42.

[0049] Fig. 8 is a perspective view of the battery module 100 of the above embodiment, with the upper FPC 51, lower FPC 52, CMU 53, upper cooling fan 61, and lower cooling fan 62 attached. Fig. 9 shows the connection 31a between the upper tab bus bar 31 and the upper FPC 51, and the connection 31b between the cell 10 and the upper tab bus bar 31, of the battery module 100 of the above embodiment. Fig. 10 shows an enlarged view of the connection 31b between the cell 10 and the upper tab bus bar 31.

[0050] 9 , the upper tab bus bar 31 is electrically connected to the upper FPC 51 at connection portion 31 a and to the plurality of cells 10 at connection portion 31 b. The first end tab bus bar 33 is electrically connected to the upper FPC 51 at connection portion 33 a and to the first general bus bar 41 at connection portion 33 b. The upper tab bus bar 31 and the first end tab bus bar 33 are connected to the FPC 51 via conductor portions 51 a, 51 b of the FPC 51. Although not shown, the lower tab bus bar 32 is electrically connected to the lower FPC 52 by a connection structure similar to that of the connection between the upper tab bus bar 31 and the upper FPC 51.

[0051] The connection portion 31a between the upper tab bus bar 31 and the upper FPC 51 can be connected by soldering or welding. For this purpose, the connection portion 31a provided on the upper tab bus bar 31 has an island-like shape with its periphery removed. Furthermore, the island-like connection portion 31a is connected to the rest of the upper tab bus bar 31 by a constricted portion having a width narrower than the width of the central portion of the island. This shape prevents heat from diffusing from the welded portion to the upper tab bus bar 31 during welding. The same applies to the connection portion 33a between the first end tab bus bar 33 and the upper FPC 51.

[0052] The upper FPC 51 is electrically connected to the CMU 53 , which allows the CMU 53 to monitor the voltages of the upper tab bus bar 31 and the first end tab bus bar 33 .

[0053] Although not shown, the lower tab bus bar 32 and the lower FPC 52 are electrically connected in the same manner as the upper tab bus bar 31 and the upper FPC 51, and the lower FPC 52 is electrically connected to the CMU 53. Although not shown, the second end tab bus bar 34 and the upper FPC 51 are electrically connected in the same manner as the first end tab bus bar 33 and the upper FPC 51.

[0054] 9, the upper tub bus bar 31 is connected to the plurality of cells 10 at a plurality of connection portions 31b each having a T-shaped slit. The first end tub bus bar 33 is also connected to the first general bus bar 41 at a connection portion 33b each having a T-shaped slit.

[0055] These connection portions having T-shaped slits are advantageous because they can reduce the generation of reactive current when spot welding them. Furthermore, such T-shaped slits mean that the connection portions do not completely cover the electrodes of the cells 10. Therefore, even if a gas leak or the like occurs from the cells 10, which are lithium-ion secondary batteries, a gas flow path is ensured, thereby improving the safety of the battery module 100.

[0056] As shown in detail in FIG. 10 , when spot welding the battery cell 10 and the upper tab bus bar 31 using four dowels 31d1 to 31d4, if current is passed through the first dowel 31d1 and the second dowel 31d2, the current flows directly through the plate-shaped portion 31e between the first dowel 31d1 and the second dowel 31d2, resulting in reactive current that does not contribute to the spot welding. However, as in this embodiment, by forming a slit between the two dowels to be welded and then spot welding them, we found that reactive current can be significantly reduced. In fact, when spot welding was performed between the first dowel 31d1 and the third dowel 31d3 across the T-shaped slit 31c, effective welding was achieved. Furthermore, by spot welding the second dowel 31d2 and the fourth dowel 31d4, the battery cell 10 and the upper tab bus bar 31 are connected at a total of four points, thereby improving the reliability of the electrical connection.

[0057] Fig. 11 shows an example of a connection portion 31b between a cell 10 and an upper tab bus bar 31. As shown in Fig. 11, the T-shaped slits 31c allow the distance 31g between the horizontal bars of the T to be adjusted between adjacent T-shaped slits 31c. Fig. 11(a) shows an embodiment in which the distance 31g between the horizontal bars of the T is appropriate, and Fig. 11(b) shows an embodiment in which the distance 31g between the horizontal bars of the T is very close.

[0058] If the distance 31g between the horizontal bars of the T is very short as in Figure 11(b), the current density from the cell may become excessively large and heat may be generated between the horizontal bars of the T (distance 31g). However, if the distance 31g between the horizontal bars of the T is appropriate as in Figure 11(a), such heat generation can be prevented.

[0059] For example, if the cell 10 is a 21700 battery with a voltage of 3.6 V and a capacity of 5 Ah, the distance 31g between the horizontal bars of the T-shape can be 5 mm or more, 8 mm or more, or 10 mm or more, and can be 30 mm or less, 20 mm or less, or 15 mm or less. For example, the distance 31g can be in the range of 10 mm or more and 15 mm or less.

[0060] Similarly, the connection portion 33b between the first end tab bus bar 33 and the first total bus bar 41 is connected by spot welding at four points across the T-shaped slit 31c.

[0061] 10, the connection portion 31b between the cell 10 and the upper tab bus bar 31 can be provided with a step 31f that steps downward from the plane of the upper tab bus bar 31. This ensures that the plate-shaped portion 31e is pressed against the cell 10 and maintains constant contact between the cell 10 and the four dowels 31d1 to 31d4 even if the cell 10 is positioned unevenly in the vertical direction, allowing spot welding to be performed without any problems. Furthermore, with this configuration, the step 31f can absorb the impact of vibrations.

[0062] It is also possible to eliminate such a step 31f at the connection portion 33b between the first end tab bus bar 33 and the first general bus bar 41. This is because the first general bus bar 41 is less likely to have variations in its vertical position, as is the case with the cells 10.

[0063] On the other hand, as shown in Fig. 12 , the first general busbar 41 has a countersunk portion 41a at the connection portion 33b, where the wall thickness is thinner on the back side. Fig. 12 shows the structure of the back side of the general busbar 41 in the battery module 100 described above. Fig. 12 shows the first general busbar 41 in the state shown in Fig. 9 in an upside-down state, and the first general busbar 41 can be welded to the first end tab busbar 33 on the side opposite the countersunk portion 41a at the portion of the first general busbar 41 where the countersunk portion 41a is located. This prevents heat diffusion during welding in the first general busbar 41, and allows for effective welding between the first general busbar 41 and the first end tab busbar 33.

[0064] Furthermore, the first general bus bar 41 may have a through hole 41b at the center of the countersunk portion 41a. By having such a through hole 41b, an automatic welding machine can position the welding portion by image recognition using the through hole 41b as an index.

[0065] Although not shown, the lower tub bus bar 32 and the plurality of cells 10 are electrically connected in the same manner as the upper tub bus bar 31 and the plurality of cells 10. Although not shown, the second end tub bus bar 34 and the second general bus bar 42 are electrically connected in the same manner as the first end tub bus bar 33 and the first general bus bar 41. In addition, although not shown, the second general bus bar 42 also has a counterbore and a through hole for the same purpose as the first general bus bar 41.

[0066] A pair of external connection parts 41c, 42c are integrally provided at one longitudinal end of the first general bus bar 41 and the second general bus bar 42. The external connection parts 41c, 42c serve as electrodes for supplying power from the cells 10 of the battery module 100 to the outside and / or for supplying power from the outside to charge the cells 10. The external connection parts 41c, 42c are arranged so as to be exposed to the outside of the case 80 from a pair of windows 80a, 80b provided in the case 80 of the battery module 100, and are configured to be electrically connectable to other battery modules 100 via the battery module bus bar 200.

[0067] <FPC and CMU> The battery module 100 includes an FPC 50 that connects to the bus bars 30, and a CMU 53 that connects to the FPC 50 and monitors the voltage and other parameters of the bus bars 30. The configurations of the FPC and the CMU are well known in the art. By connecting the FPC 50 to a thermistor, the CMU 53 can also monitor the temperature within the battery module 100.

[0068] The FPC 50 is composed of an upper FPC 51 that connects to the upper tab bus bar 31 and the first and second end tab bus bars 33, 34, and a lower FPC 52 that connects to the lower tab bus bar 32. The upper FPC 51 and the lower FPC 52 are connected to one CMU 53.

[0069] <Cooling Fan> The battery module 100 is provided with a cooling fan 60 for cooling the built-in heat-generating cells 10. The installation position of the cooling fan 60 is not particularly limited as long as it can cool the cells 10.

[0070] For example, in the above embodiment, the cooling fan 60 can be configured with an upper cooling fan 61 that sends cooling air to an area (upper space 101) above the holder 20 in the battery module 100, and a lower cooling fan 62 that sends cooling air to an area (lower space 102) below the holder 20. By using two cooling fans 61, 62 sandwiching the holder 20 in this way, the cells 10 can be cooled separately in two areas within the battery module 100. In this case, the upper cooling fan 61 and the lower cooling fan 62 can be configured to blow air in directions facing each other. Furthermore, the upper cooling fan 61 and the lower cooling fan 62 can also be configured to be located at diagonal positions on the battery module 100.

[0071] 13 is a conceptual diagram of a structure for cooling the cells 10 in a battery module 100 with a cooling fan 60. As conceptually shown in FIG. 13 , cooling air is sent by a cooling fan 61 (not shown) from an inlet located at a corner of an upper space 101 above the holder 20 in the housing 80 of the battery module 100, and the cooling air hits the portions of the plurality of cells 10 exposed in the upper space 101 to cool them (exchange heat), and then the warmed cooling air can be discharged from an outlet located diagonally in the upper space 101. Also, cooling air is sent by a cooling fan 62 (not shown) from an inlet located at a corner of a lower space 102 below the holder 20 in the housing 80, and the cooling air hits the portions of the plurality of cells 10 exposed in the lower space 102 to cool them (exchange heat), and then the warmed cooling air can be discharged from an outlet located diagonally in the lower space 102.

[0072] Here, the inlet of the upper space 101 and the outlet of the lower space 102, and the outlet of the upper space 101 and the inlet of the lower space 102, can be positioned above and below each other. This configuration allows the multiple unit cells 10 to be cooled relatively uniformly regardless of their positions. That is, for unit cells 10 close to the inlet of the upper space 101, the portions exposed to the upper space 101 are subjected to relatively low-temperature cooling air and are therefore strongly cooled. On the other hand, since the unit cells 10 are located far from the inlet of the lower space 102, the portions exposed to the lower space 102 are subjected to relatively high-temperature cooling air that has already cooled the unit cells 10 located close to the inlet of the lower space 102, and are therefore not strongly cooled. However, as a whole, heat transfers from the portions exposed to the lower space 102 to the portions exposed to the upper space 101, so the portions exposed to the lower space 102 do not become too hot. Furthermore, even if there is a bias in the ambient temperature around the battery cells 10 depending on the location in the upper space 101 and the lower space 102, the air in the upper space 101 and the lower space 102 is agitated by the air blown by the cooling fans 61 and 62, so that the bias in the ambient temperature around the battery cells 10 depending on the location in the upper space 101 and the lower space 102 can be reduced.

[0073] The cooling fan 60 can also be positioned so as to actively cool the metal electrodes and bus bars 30 at the axial ends of the cells 10. This configuration allows the cooling air to be directed at the metal parts, which have higher cooling efficiency, rather than the body parts of the cells 10 covered with a film.

[0074] Fig. 14 shows a conceptual cross-sectional view of a structure for cooling the cells 10 in a battery module with cooling fans 60. As conceptually shown in Fig. 14, the upper cooling fan 61 can be positioned in the upper space 101 so as to blow cooling air onto the electrodes on one side at the axial end of the cells 10 and the metal portion of the upper tub bus bar 31, and the lower cooling fan 62 can be positioned in the lower space 102 so as to blow cooling air onto the electrodes on the other side at the axial end of the cells 10 and the metal portion of the lower tub bus bar 32.

[0075] <Others> The battery module 100 includes a bracket 70 for fixing to, for example, the frame 400 of the battery pack 1000. The bracket 70 is configured so that most of it is stored inside the housing 80, but only the portion that is fixed to the frame 400 or the like is exposed to the outside of the housing 80. In the above embodiment, the bracket 70 is configured by a first bracket 71 and a second bracket 72 that are located at both ends in the y direction inside the battery module 100.

[0076] The battery module 100 is covered from the outside by a housing 80 to protect the inside. In the above embodiment, the housing 80 is composed of an upper housing 81 and a lower housing 82.

[0077] The present invention can have the following aspects.

[0078] <<Aspect 1>> One aspect of the present invention relates to an assembled battery comprising a plurality of single cells, a holder having a plurality of retaining holes that accommodate the single cells, and an adhesive that bonds the single cells to the retaining holes, wherein the holder has a plurality of adhesive-filled portions therein, and at least some of the plurality of retaining holes are in communication with two or more of the adhesive-filled portions.

[0079] In this embodiment, adhesive is filled from two or more adhesive filling sections into the gap between the cell and the retaining hole that houses the cell. Even if the adhesive filling from one adhesive filling section is insufficient, the battery can be securely bonded as long as the adhesive filling from the other adhesive filling sections is sufficient. Furthermore, because the adhesive filling sections are located inside the holder, the battery can be securely bonded without being filled only at the edge of the battery. Furthermore, this configuration allows for the manufacture of a battery pack without the need for a process of inverting the holder and injecting adhesive, as is done in conventional technology. Furthermore, by adhesively fixing the cell to the retaining hole at two or more locations within the retaining hole, or by adhesively fixing the cell to the retaining hole around the entire circumference, wear between the battery and the inner periphery of the holder can be prevented, resulting in a structure that is resistant to vibration.

[0080] <<Aspect 2>> In the above aspect, at least some of the plurality of adhesive-filled portions communicate with two or more of the holding holes.

[0081] One aspect of the present invention relates to an assembled battery comprising a plurality of single cells, a holder having a plurality of retaining holes for accommodating the single cells, and an adhesive for bonding the single cells to the retaining holes, wherein the holder has a plurality of adhesive-filled portions therein, and at least some of the plurality of adhesive-filled portions are in communication with two or more of the retaining holes.

[0082] In this embodiment, by filling one adhesive filling portion with adhesive, the gaps between the cells and the plurality of retaining holes that house the cells can be filled with adhesive, making it extremely easy to fill the adhesive. Furthermore, in this embodiment, if the plurality of retaining holes are connected to two or more adhesive filling portions, even if there is variation in the amount of adhesive filled in one adhesive filling portion, as long as there is sufficient adhesive filled in the other adhesive filling portions, the batteries can be adhered and fixed without any problems, which is very advantageous.

[0083] <<Aspect 3>> In the above aspect, the holder has an upper holder and a lower holder, and the adhesive filling portion is located between the lower surface of the upper holder and the upper surface of the lower holder.

[0084] In this embodiment, the adhesive filling portion is present between the upper holder and the lower holder, so that the adhesive filling portion can be easily formed. Also, in this embodiment, the adhesive is filled in the gaps between the unit cell, the upper holder, and the lower holder, so that they can have high rigidity as a single structure, which is advantageous.

[0085] <<Aspect 4>> In the above aspect, the adhesive filling portion is located between the recessed portion and the protruding portion formed on the lower surface of the upper holder and the upper surface of the lower holder.

[0086] In this embodiment, the upper and lower holders can be easily combined using the recessed and protruding portions of the adhesive-filled portion. Furthermore, the presence of a protruding portion in the adhesive-filled portion is advantageous because it facilitates the flow of the filled adhesive into the holding hole that communicates with the adhesive-filled portion. In this embodiment, the upper holder may have either a recessed or protruding portion, but the lower holder may have a protruding or recessed portion that can fit into the recessed or protruding portion of the upper holder.

[0087] <<Aspect 5>> In the above aspect, the recessed portion and the protruding portion each have a conical shape.

[0088] In this embodiment, if the recessed portion and the protruding portion have conical shapes that can fit together, even if the upper and lower holders are fitted together in slightly different positions, the downward conical shape of the recessed portion and the upward conical shape of the protruding portion slide against each other, ensuring reliable alignment at the intended positions. As a result, fitting the upper and lower holders together can be made very easy. Also, the adhesive placed in the recessed portion can be smoothly extruded by the protruding portion.

[0089] <<Aspect 6>> In the above aspect, the adhesive filling portion does not have to be in communication with the upper surface of the upper holder and the lower surface of the lower holder.

[0090] In this embodiment, the adhesive can be applied to the adhesive-filled portion from the underside of the upper holder and / or the top side of the lower holder. In this case, the upper and lower holders can be assembled after the adhesive is applied to the adhesive-filled portion. In this embodiment, the adhesive can be applied to the adhesive-filled portion very easily, even if the viscosity of the adhesive used is relatively high, and a constant amount of adhesive can be applied to the adhesive-filled portion. Furthermore, by assembling the upper and lower holders, the adhesive can be extruded all at once from the multiple adhesive-filled portions into the gaps between the multiple unit cells and the multiple holding holes that house the unit cells, allowing multiple unit cells to be bonded and fixed at one time.

[0091] <<Aspect 7>> In the above aspect, the upper surface of the upper holder and / or the lower surface of the lower holder has an adhesive injection hole that communicates with the adhesive filling portion.

[0092] In this embodiment, after the upper holder and the lower holder are combined, adhesive can be injected from the adhesive injection hole into the adhesive filling portion.

[0093] <<Aspect 8>> In the above aspect, the upper retaining hole of the upper holder has a tapered upper wall surface whose diameter expands from the top surface to the bottom surface, and the lower retaining hole of the lower holder has a tapered lower wall surface whose diameter expands from the bottom surface to the top surface.

[0094] In this embodiment, the adhesive is sufficiently and smoothly filled from the adhesive filling portion into the gaps provided on the outer periphery of the unit cells, thereby ensuring reliable adhesive fixation of the unit cells.

[0095] <<Aspect 9>> In the above aspect, the holder holds the unit cell at a substantially central position in the axial direction of the unit cell.

[0096] In this embodiment, the positive and negative electrodes of the cells can be positioned in the spaces separated by the holder. This allows for efficient cooling of the heat-generating electrode portions of the cells. Furthermore, by holding the cells at approximately the middle position with the holder, the cells are fixed near their centers of gravity, making the structure resistant to vibration.

[0097] Aspect 10 One aspect of the present invention relates to a battery module including: a battery pack; a bus bar that electrically connects electrodes of a plurality of unit cells of the battery pack; and a cooling fan that cools the plurality of unit cells of the battery pack.

[0098] The battery pack used in this embodiment may be the battery pack of the above embodiment. In particular, this battery pack may be one in which the holder holds the plurality of unit cells at approximately the middle position in the axial direction of the unit cells.

[0099] <<Aspect 11>> In the above aspect, the cooling fan is configured to cool the electrodes of the plurality of electric cells and the bus bar.

[0100] In this embodiment, the cooling fan is configured to actively cool the electrodes and bus bars, which are more easily cooled, thereby improving cooling efficiency. The body of the unit cell is usually covered with an insulating film and is therefore difficult to cool, whereas the electrodes and bus bars of the unit cell are made of metal and can be cooled effectively.

[0101] <<Aspect 12>> In the above aspect, the cooling fans are arranged in the upper space above the holder and in the lower space below the holder, and the upper cooling fan in the upper space and the lower cooling fan in the lower space are configured to blow air in directions facing each other.

[0102] While cells located near the cooling fan in the upper space can be effectively cooled in the upper space, cells located far from the cooling fan in the upper space cannot be effectively cooled because they are exposed to warm air that has cooled the cells. However, in this embodiment, cells located far from the cooling fan in the upper space are effectively cooled in the lower space by locating the cooling fan in a position close to the cells. As a result, variations in cooling among multiple cells can be reduced. This embodiment is extremely advantageous because the holder's holding holes must be manufactured with extremely high precision to provide space for the cells and adhesive, and thermal expansion can be a problem.

[0103] Aspect 13 One aspect of the present invention relates to a battery pack including a plurality of battery modules as described above, and a battery module bus bar that electrically connects the plurality of battery modules.

[0104] Such a battery pack is advantageous because the cells can be easily and securely fixed.

[0105] Aspect 14 One aspect of the present invention relates to a method for manufacturing a battery pack as described in Aspect 6 above, including: placing adhesive in an adhesive filling portion of at least one of the upper holder or the lower holder; and assembling the upper holder and the lower holder with the plurality of single cells housed in the retaining holes, and allowing the adhesive to flow into the retaining holes that are connected to the adhesive filling portion.

[0106] In this embodiment, the adhesive can be placed in the adhesive-filled portion from the underside of the upper holder and / or the top side of the lower holder, and since the adhesive can be injected or placed in the adhesive-filled portion very easily, a relatively high viscosity of the adhesive used does not pose a problem, and a constant amount of adhesive can be placed in the adhesive-filled portion. Furthermore, by combining the upper holder and the lower holder, the adhesive can be extruded all at once from the multiple adhesive-filled portions into the gaps between the multiple unit cells and the multiple holding holes that house the unit cells, so that multiple unit cells can be adhered and fixed at one time.

[0107] DESCRIPTION OF SYMBOLS 10, 11, 12... Cell 20, 21, 22... Holder, upper holder, lower holder 20a, 21a, 22a... Retaining hole, upper retaining hole, lower retaining hole 20b, 21b, 22b... Adhesive filling portion (convex portion, concave portion) 21c, 22c... Wall surface of retaining hole (upper wall surface, lower wall surface) 21d, 22d... Upper surface of upper holder, upper surface of lower holder 21e, 22e... Lower surface of upper holder, lower surface of lower holder 21f... Adhesive injection hole ad... Adhesive 30, 40... Busbar (tab busbar, total busbar) 31, 32... Upper tab busbar, lower tab busbar 31a... Connection portion between upper tab busbar and upper FPC 31b... Connection portion between upper tab busbar and cell 31c... T-shaped slit 31d1 to 31d4... First to fourth dowels 31e...Plate-shaped portion 31f...Step 31g...Distance between horizontal bars of T-shape 33, 34...First end tab bus bar, second end tab bus bar 33a...Connection portion between first end tab bus bar and upper FPC 33b...Connection portion between first end tab bus bar and first general bus bar 41, 42...First general bus bar, second general bus bar 41a...Counterbore portion 41b...Through hole 41c, 42c...Electrodes (external connection portion) 50, 51, 52...FPC, upper FPC, lower FPC 51a...Connection portion between upper tab bus bar and upper FPC 51b...Connection portion between first end tab bus bar and upper FPC 53...CMU 60, 61, 62...Cooling fan, upper cooling fan, lower cooling fan 70, 71, 72...Bracket, first bracket, second bracket DESCRIPTION OF THE REFERENCE NUMERALS 80, 81, 82... Housing, upper housing, lower housing 80a, 80b... Window portion 100... Battery module 101, 102... Upper space, lower space 200... Bus bar for battery module 301... Control device 302... Connectors 400... Frame 501 to 506... Exterior panels 1000... Battery pack

Claims

1. A battery pack comprising a plurality of single cells, a holder having a plurality of holding holes for accommodating the single cells, and an adhesive for adhering the single cells and the holding holes, wherein the holder has a plurality of adhesive filling portions inside, and at least a part of the plurality of holding holes communicates with two or more of the adhesive filling portions.

2. The battery pack according to claim 1, wherein at least a part of the plurality of adhesive filling portions communicates with two or more of the holding holes.

3. The battery pack according to claim 1, wherein the holder has an upper holder and a lower holder, and the adhesive filling portion is located between the lower surface of the upper holder and the upper surface of the lower holder.

4. The battery pack according to claim 3, wherein the adhesive filling portion is located between a concave portion and a convex portion formed on the lower surface of the upper holder and the upper surface of the lower holder.

5. The battery pack according to claim 4, wherein the concave portion and the convex portion each have a conical shape.

6. The battery pack according to claim 3, wherein the adhesive filling portion does not communicate with the upper surface of the upper holder and the lower surface of the lower holder.

7. The battery pack according to claim 3, wherein the upper surface of the upper holder and / or the lower surface of the lower holder has an adhesive injection hole communicating with the adhesive filling portion.

8. The battery pack according to claim 3, wherein the upper holding hole of the upper holder has an upper wall surface with a tapered shape whose diameter expands from the upper surface to the lower surface, and the lower holding hole of the lower holder has a lower wall surface with a tapered shape whose diameter expands from the lower surface to the upper surface.

9. The battery pack according to claim 1, wherein the holder holds the single cells at a substantially intermediate position in the axial direction of the single cells.

10. A battery module comprising the battery pack according to claim 9, a bus bar for electrically connecting the electrodes of the plurality of single cells, and a cooling fan for cooling the plurality of single cells.

11. The battery module according to claim 10, wherein the cooling fan is configured to cool the electrodes of the plurality of single cells and the bus bar.

12. The battery module according to claim 11, wherein the cooling fan is disposed in each of an upper space above the holder and a lower space below the holder, and the upper cooling fan in the upper space and the lower cooling fan in the lower space are configured to blow air in directions facing each other.

13. A battery pack comprising the plurality of battery modules according to claim 10 and a bus bar for battery modules that electrically connects the plurality of battery modules.

14. A method for manufacturing an assembled battery according to claim 6, the method including: disposing an adhesive in at least one of the adhesive filling portions of the upper holder or the lower holder; and combining the upper holder and the lower holder with the plurality of single cells accommodated in the holding holes, and causing the adhesive to flow out into the holding holes in communication with the adhesive filling portions.

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