Power storage device

Abstract

A power storage device according to the present invention comprises: a cell assembly provided with a first cell unit comprising a plurality of cylindrical cells and a second cell unit comprising a plurality of cylindrical cells; and a bus bar group connecting the first cell unit and the second cell unit to each other. The bus bar group includes a positive electrode bus bar disposed at a first end in the longitudinal direction of the cell assembly and connected to positive electrodes of the first cell unit. The bus bar group includes a negative electrode bus bar disposed at the first end of the cell assembly and connected to negative electrodes of the second cell unit. The bus bar group further includes an intermediate bus bar disposed at a second end in the longitudinal direction of the cell assembly and connecting the negative electrodes of the first cell unit and the positive electrodes of the second cell unit to each other.

Description

Power storage device

[0001] The present disclosure relates to an electricity storage device.

[0002] Electric vehicles, hybrid vehicles, etc. have a battery pack including a battery module, a controller, etc. The battery module, i.e., the power storage device, incorporated into the battery pack has a plurality of cylindrical cells as battery cells (see Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2024-618

[0004] In some cases, a positive terminal is provided at one end of a battery module and a negative terminal is provided at the other end of the battery module. However, providing positive and negative terminals at both ends of the battery module complicates wiring using bus bars and cables. Therefore, there is a need to simplify the wiring of the battery module, i.e., the power storage device.

[0005] According to the present disclosure, an energy storage device includes a cell assembly including a first cell unit consisting of a plurality of cylindrical cells and a second cell unit arranged adjacent to the first cell unit and consisting of a plurality of cylindrical cells. The energy storage device includes a busbar group arranged opposite electrode surfaces of the cell assembly and connecting the first cell unit and the second cell unit to each other. The busbar group includes a positive busbar arranged at a first longitudinal end of the cell assembly and connected to the positive electrode of the first cell unit. The busbar group includes a negative busbar arranged at the first end of the cell assembly and connected to the negative electrode of the second cell unit. The busbar group includes an intermediate busbar arranged at a second longitudinal end of the cell assembly and connecting the negative electrode of the first cell unit to the positive electrode of the second cell unit to each other.

[0006] According to the present disclosure, it is possible to simplify the wiring of the power storage device.

[0007] FIG. 1 is a diagram illustrating an example of a vehicle. FIG. 2 is a diagram illustrating an example of the configuration of a battery pack. FIG. 3 is an exploded perspective view of a battery module. FIG. 4 is a simplified diagram of a battery module. FIG. 5 is a diagram illustrating a cell assembly, an insulating plate, and a bus bar group as viewed from the direction of arrow A1 in FIG. 3. FIG. 6 is a diagram illustrating a bus bar group as viewed from the direction of arrow A1 in FIG. 3. FIG. 7 is an enlarged view of a range F7 illustrated in FIG. 5. FIG. 8 is an enlarged view of a range F8 illustrated in FIG. 5. FIG. 9 is an enlarged view of a range F9 illustrated in FIG. 5. FIG. 10 is an enlarged view of a range F10 illustrated in FIG. 5. FIG. 11 is a diagram illustrating a connection state of a cell group using a bus bar group. FIG. 12 is a diagram illustrating a modified example of a cell assembly and a bus bar group. FIG. 13 is a diagram illustrating a modified example of a bus bar group. FIG. 14 is an enlarged view of a range F14 illustrated in FIG. 12. FIG. 15 is an enlarged view of a range F15 illustrated in FIG. 12. FIG. 16 is an enlarged view of a range F16 illustrated in FIG. 12. FIG. 17 is an enlarged view of a range F17 illustrated in FIG. 12.

[0008] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings. In the following description, identical or substantially identical configurations and elements are designated by the same reference numerals and will not be described repeatedly.

[0009] <Vehicle> Fig. 1 is a diagram showing an example of a vehicle 10. The vehicle 10 shown in Fig. 1 includes a battery pack 14 incorporating an electric storage device according to an embodiment of the present disclosure. As shown in Fig. 1, the vehicle 10 has an electric axle 13 including an electric motor 11 and a differential mechanism 12, and a battery pack 14 provided under the vehicle body. The battery pack 14 is connected to the electric motor 11 of the electric axle 13 via an inverter 15. The battery pack 14 is also connected to a cooling system 18 including a water pump 16 and a radiator 17. The differential mechanism 12 of the electric axle 13 is coupled to wheels 20 via axles 19.

[0010] <Battery Pack> Fig. 2 is a diagram showing an example of the configuration of the battery pack 14. As shown in Fig. 2, the battery pack 14 includes a battery case 21, a plurality of battery modules (power storage devices) 22, 23 housed in the battery case 21, and a junction box 24 provided in the battery case 21. The junction box 24 is provided with a terminal block 25, high-voltage connectors 26, 27, an electronic control unit 28, and the like. The inverter 15 is connected to the high-voltage connectors 26, 27 of the junction box 24 via high-voltage cables 29, 30.

[0011] The positive terminal plate 22a of the battery module 22 is connected to the positive electrode connection portion 25a of the terminal block 25 via a module bus bar 31a, and the negative terminal plate 22b of the battery module 22 is connected to the negative electrode connection portion 25b of the terminal block 25 via a module bus bar 31b. Similarly, the positive terminal plate 23a of the battery module 23 is connected to the positive electrode connection portion 25a of the terminal block 25 via a module bus bar 32a, and the negative terminal plate 23b of the battery module 23 is connected to the negative electrode connection portion 25b of the terminal block 25 via a module bus bar 32b.

[0012] In the illustrated example, the battery pack 14 is provided with two battery modules 22, 23, but this is not limited thereto, and the battery pack 14 may be provided with one battery module, or may be provided with three or more battery modules. In the illustrated example, the battery modules 22, 23 are connected in parallel to each other, but this is not limited thereto, and the battery modules 22, 23 may be connected in series to each other.

[0013] The cooling system 18 includes a water pump 16 that pumps coolant and a radiator 17 that serves as a heat exchanger. A discharge pipe 34 is connected to a discharge port 16a of the water pump 16, and a suction pipe 36 is connected to a suction port 16b of the water pump 16 via a connection pipe 35 and the radiator 17. The discharge pipe 34a branching from the discharge pipe 34 is connected to a joint 37 of the battery module 22, and the discharge pipe 34b branching from the discharge pipe 34 is connected to a joint 38 of the battery module 23. The suction pipe 36a branching from the suction pipe 36 is connected to a joint 39 of the battery module 22, and the suction pipe 36b branching from the suction pipe 36 is connected to a joint 40 of the battery module 23.

[0014] <Battery Module> In the above description, the battery modules are denoted by the reference numerals 22 and 23, the positive terminal plates are denoted by the reference numerals 22a and 23a, and the negative terminal plates are denoted by the reference numerals 22b and 23b. However, in the following description, the battery modules are denoted by the reference numeral 50, the positive terminal plates are denoted by the reference numeral 50a, and the negative terminal plates are denoted by the reference numeral 50b.

[0015] FIG. 3 is an exploded perspective view showing the battery module 50. Because the battery module 50 has an elongated shape, FIG. 3 shows both ends of the battery module 50 and their vicinity. FIG. 4 is a simplified view of the battery module 50, and FIG. 5 is a view showing the cell assembly 56, insulating plates 58, and bus bar group 59 from the direction of arrow A1 in FIG. 3. FIG. 6 is a view showing the bus bar group 59 from the direction of arrow A1 in FIG. 3. FIG. 7 is an enlarged view of a range F7 shown in FIG. 5, and FIG. 8 is an enlarged view of a range F8 shown in FIG. 5. Note that, like FIG. 3, FIGS. 5 and 6 also show both ends of the cell assembly 56 and the bus bar group 59 and their vicinity.

[0016] As shown in FIG. 3 , the battery module (electricity storage device) 50 has a housing 54 consisting of an upper cover 51, a lower cover 52, and a side cover 53. The housing 54 accommodates a cell assembly 56 consisting of a number of cylindrical cells 55, as well as an insulating plate 58 attached to an electrode surface 57 at the lower end of the cell assembly 56. The housing 54 also accommodates a bus bar group 59 disposed between the insulating plate 58 and the lower cover 52. The bus bar group 59 faces the electrode surface 57 of the cell assembly 56. The bus bar group 59 includes a plurality of bus bars 65, 66, 67, 81, 82, 83, and 84, each of which is made of a metal plate such as an aluminum alloy. A positive terminal plate 50a is integrally formed with the bus bar 65, and a negative terminal plate 50b is integrally formed with the bus bar 66.

[0017] <Cell Unit and Cell Group> As shown in Fig. 4, the battery module 50 has a cell assembly 56 housed in a housing 54. This cell assembly 56 has a cell unit (first cell unit) 61 consisting of a plurality of cylindrical cells 55, and a cell unit (second cell unit) 62 consisting of a plurality of cylindrical cells 55. The cell unit 61 and the cell unit 62 are arranged adjacent to each other in the width direction D2 of the cell assembly 56. In other words, the cell unit 61 and the cell unit 62 are arranged parallel to each other.

[0018] As shown in FIG. 5 , the cell unit 61 of the cell assembly 56 includes a plurality of cell groups (first cell group) 71 each including a plurality of cylindrical cells 55, and a plurality of cell groups (second cell group) 72 each including a plurality of cylindrical cells 55. The cell groups 71 and 72 are arranged alternately in the longitudinal direction D1 of the cell assembly 56. Similarly, the cell unit 61 of the cell assembly 56 includes a plurality of cell groups (third cell group) 73 each including a plurality of cylindrical cells 55, and a plurality of cell groups (fourth cell group) 74 each including a plurality of cylindrical cells 55. The cell groups 73 and 74 are arranged alternately in the longitudinal direction D1 of the cell assembly 56. A potting material (not shown) is injected into the gaps between the cylindrical cells 55 in the cell assembly 56.

[0019] <Busbar Group> As shown in Figure 5, the busbar group 59 includes a positive busbar 65 arranged at an end (first end) 56a of the cell assembly 56 in the longitudinal direction D1, a negative busbar 66 arranged at the end 56a of the cell assembly 56 in the longitudinal direction D1, and an intermediate busbar 67 arranged at an end (second end) 56b of the cell assembly 56 in the longitudinal direction D1. The positive busbar 65 includes a plate portion 65a and a plurality of parallel bar portions 65b extending linearly from the plate portion 65a in the longitudinal direction D1. The negative busbar 66 includes a plate portion 66a and a plurality of parallel bar portions 66b extending linearly from the plate portion 66a in the longitudinal direction D1. The intermediate busbar 67 includes a plate portion 67a and a plurality of parallel bar portions 67b extending linearly from the plate portion 67a in the longitudinal direction D1.

[0020] The bus bar group 59 has a plurality of cell bus bars 81 and a plurality of cell bus bars 82 to connect the plurality of cylindrical cells 55 that make up the cell unit 61 to one another. That is, the bus bar group 59 has a plurality of cell bus bars (first bus bars) 81 that are arranged between the end 56 a and the end 56 b of the cell assembly 56. The bus bar group 59 also has a plurality of cell bus bars (second bus bars) 82 that are arranged between the end 56 a and the end 56 b of the cell assembly 56. The cell bus bars 81 and the cell bus bars 82 are arranged alternately in the longitudinal direction D1 of the cell assembly 56.

[0021] Similarly, the bus bar group 59 has a plurality of cell bus bars 83 and a plurality of cell bus bars 84 to connect the plurality of cylindrical cells 55 that make up the cell unit 62 to one another. That is, the bus bar group 59 has a plurality of cell bus bars (third bus bars) 83 that are arranged between the end 56 a and the end 56 b of the cell assembly 56. The bus bar group 59 also has a plurality of cell bus bars (fourth bus bars) 84 that are arranged between the end 56 a and the end 56 b of the cell assembly 56. The cell bus bars 83 and the cell bus bars 84 are arranged alternately in the longitudinal direction D1 of the cell assembly 56.

[0022] 4 , separators 68 are provided between cell units 61 and 62. That is, separators 68 are provided between the positive bus bar 65 and the negative bus bar 66, between the cell bus bar 81 and the cell bus bar 83, and between the cell bus bar 82 and the cell bus bar 84. By arranging separators 68 in this manner, short circuits between the positive bus bar 65 and the negative bus bar 66, between the cell bus bar 81 and the cell bus bar 83, and between the cell bus bar 82 and the cell bus bar 84 are prevented.

[0023] As shown in Fig. 6, the cell bus bar 81 includes a plurality of parallel bar portions (first parallel bar portions) 81a arranged parallel to one another and a plurality of connecting bar portions (first connecting bar portions) 81b connecting the parallel bar portions 81a to one another. The parallel bar portions 81a extend linearly in the longitudinal direction D1 of the cell assembly 56, while the connecting bar portions 81b extend linearly in a direction inclined relative to the longitudinal direction D1. As shown in Fig. 7, the connecting bar portions 81b extend substantially parallel to an imaginary line L1 connecting the centers of adjacent cylindrical cells 55 in the width direction D2 of the cell assembly 56. As will be described later, the parallel bar portions 81a of the cell bus bar 81 are connected to the positive electrode of the cell group 71 and the negative electrode of the cell group 72.

[0024] The cell bus bar 82 includes a plurality of parallel bar portions (second parallel bar portions) 82a arranged parallel to one another and a plurality of connecting bar portions (second connecting bar portions) 82b connecting the parallel bar portions 82a to one another. The parallel bar portions 82a extend linearly in the longitudinal direction D1 of the cell assembly 56, while the connecting bar portions 82b extend linearly in a direction inclined relative to the longitudinal direction D1. As shown in FIG. 7 , the connecting bar portions 82b extend substantially parallel to an imaginary line L2 connecting the centers of adjacent cylindrical cells 55 in the width direction D2 of the cell assembly 56. As will be described later, the parallel bar portions 82a of the cell bus bar 82 are connected to the positive electrode of the cell group 72 and the negative electrode of the cell group 71.

[0025] The cell bus bar 83 includes a plurality of parallel bar portions (third parallel bar portions) 83a arranged parallel to one another and a plurality of connecting bar portions (third connecting bar portions) 83b connecting the parallel bar portions 83a to one another. The parallel bar portions 83a extend linearly in the longitudinal direction D1 of the cell assembly 56, while the connecting bar portions 83b extend linearly in a direction inclined relative to the longitudinal direction D1. As shown in FIG. 8 , the connecting bar portions 83b extend substantially parallel to an imaginary line L3 connecting the centers of adjacent cylindrical cells 55 in the width direction D2 of the cell assembly 56. As will be described later, the parallel bar portions 83a of the cell bus bar 83 are connected to the positive electrode of the cell group 73 and the negative electrode of the cell group 74.

[0026] The cell bus bar 84 includes a plurality of parallel bar portions (fourth parallel bar portions) 84a arranged parallel to one another and a plurality of connecting bar portions (fourth connecting bar portions) 84b connecting the parallel bar portions 84a to one another. The parallel bar portions 84a extend linearly in the longitudinal direction D1 of the cell assembly 56, while the connecting bar portions 84b extend linearly in a direction inclined relative to the longitudinal direction D1. As shown in FIG. 8 , the connecting bar portions 84b extend substantially parallel to an imaginary line L4 connecting the centers of adjacent cylindrical cells 55 in the width direction D2 of the cell assembly 56. As will be described later, the parallel bar portions 84a of the cell bus bar 84 are connected to the positive electrode of the cell group 74 and the negative electrode of the cell group 73.

[0027] <Connection Structure of Cylindrical Cells (Enlarged View)> As shown in the enlarged portion of FIG. 7 , each of the cylindrical cells 55 constituting the cell groups 71, 72, 73, and 74 has a positive electrode terminal 55 a disposed at the center of the cell end face, and an annular negative electrode terminal 55 b disposed so as to surround the positive electrode terminal 55 a.

[0028] The connection structure of the cylindrical cells 55 using the cell bus bars 81, 82 will be described. As shown in Fig. 7 , the parallel bar portions 81a of the cell bus bar 81 are connected, via bonding wires 85, to the positive terminals (positive electrodes) 55a of the two cylindrical cells 55 that make up the cell group 71, and are also connected to the negative terminals (negative electrodes) 55b of the two cylindrical cells 55 that make up the cell group 72. Furthermore, the parallel bar portions 82a of the cell bus bar 82 are connected, via bonding wires 85, to the positive terminals (positive electrodes) 55a of the two cylindrical cells 55 that make up the cell group 72, and are also connected to the negative terminals (negative electrodes) 55b of the two cylindrical cells 55 that make up the cell group 71.

[0029] The connection structure of the cylindrical cells 55 using the cell bus bars 83, 84 will be described. As shown in Fig. 8 , the parallel bar portions 83a of the cell bus bar 83 are connected, via bonding wires 85, to the positive terminals (positive electrodes) 55a of the two cylindrical cells 55 that make up the cell group 73, and are also connected to the negative terminals (negative electrodes) 55b of the two cylindrical cells 55 that make up the cell group 74. Furthermore, the parallel bar portions 84a of the cell bus bar 84 are connected, via bonding wires 85, to the positive terminals (positive electrodes) 55a of the two cylindrical cells 55 that make up the cell group 74, and are also connected to the negative terminals (negative electrodes) 55b of the two cylindrical cells 55 that make up the cell group 73.

[0030] Fig. 9 is an enlarged view of area F9 shown in Fig. 5. The connection structure of the cylindrical cells 55 using the positive bus bar 65 and the negative bus bar 66 will be described using Fig. 9. As shown in Fig. 9, the parallel bar portions 65b of the positive bus bar 65 are each connected via bonding wires 85 to the positive terminals (positive electrodes) 55a of the two cylindrical cells 55 that make up the cell group 71. Furthermore, the parallel bar portions 66b of the negative bus bar 66 are each connected via bonding wires 85 to the negative terminals (negative electrodes) 55b of the two cylindrical cells 55 that make up the cell group 74.

[0031] Fig. 10 is an enlarged view of area F10 shown in Fig. 5. The connection structure of the cylindrical cells 55 using the intermediate bus bar 67 will be described using Fig. 10. As shown in Fig. 10, each of the parallel bar portions 67b of the intermediate bus bar 67 is connected, via bonding wires 85, to the negative terminals (negative electrodes) 55b of the two cylindrical cells 55 that make up the cell group 72, and to the positive terminals (positive electrodes) 55a of the two cylindrical cells 55 that make up the cell group 73.

[0032] <Connection Structure of Cylindrical Cells (Circuit Diagram)> Figure 11 is a diagram showing the connection state of cell groups 71, 72, 73, and 74 by bus bar group 59. As shown in Figure 11, a positive bus bar 65 arranged at end 56a of cell assembly 56 is connected to the positive electrodes of cylindrical cells 55 that make up cell group 71. A negative bus bar 66 arranged at end 56a of cell assembly 56 is connected to the negative electrodes of cylindrical cells 55 that make up cell group 74. An intermediate bus bar 67 arranged at end 56b of cell assembly 56 is connected to the negative electrodes of cylindrical cells 55 that make up cell group 72 and the positive electrodes of cylindrical cells 55 that make up cell group 73.

[0033] To interconnect the multiple cylindrical cells 55 that make up the cell unit 61, a cell bus bar 81 and a cell bus bar 82 are disposed between the end 56a and the end 56b of the cell assembly 56. The cell bus bar 81 is connected to the positive electrodes of the cylindrical cells 55 that make up the cell group 71 and the negative electrodes of the cylindrical cells 55 that make up the cell group 72. The cell bus bar 82 is connected to the positive electrodes of the cylindrical cells 55 that make up the cell group 72 and the negative electrodes of the cylindrical cells 55 that make up the cell group 71.

[0034] To interconnect the multiple cylindrical cells 55 that make up the cell unit 62, a cell bus bar 83 and a cell bus bar 84 are disposed between the end 56a and end 56b of the cell assembly 56. The cell bus bar 83 is connected to the positive electrodes of the cylindrical cells 55 that make up the cell group 73 and the negative electrodes of the cylindrical cells 55 that make up the cell group 74. The cell bus bar 84 is connected to the positive electrodes of the cylindrical cells 55 that make up the cell group 74 and the negative electrodes of the cylindrical cells 55 that make up the cell group 73.

[0035] That is, the plurality of cylindrical cells 55 constituting cell group 71 are connected in parallel to one another, and the plurality of cylindrical cells 55 constituting cell group 72 are connected in parallel to one another. Similarly, the plurality of cylindrical cells 55 constituting cell group 73 are connected in parallel to one another, and the plurality of cylindrical cells 55 constituting cell group 74 are connected in parallel to one another. Cell group 71, cell group 72, cell group 73, and cell group 74 are connected in series to one another.

[0036] 11 , an intermediate bus bar 67 is provided at the end 56b of the cell assembly 56, and this intermediate bus bar 67 connects the negative electrode of the cell unit 61 and the positive electrode of the cell unit 62 to each other. This allows the positive electrode of the cell unit 61 and the negative electrode of the cell unit 62 to be gathered at the end 56a of the cell assembly 56, and the positive electrode bus bar 65 and the negative electrode bus bar 66 to be gathered at the end 56a of the cell assembly 56. In other words, the positive electrode terminal plates 50a and the negative electrode terminal plates 50b of the battery module 50 can be gathered on one side in the longitudinal direction of the battery module 50, thereby simplifying the wiring of the battery module 50.

[0037] That is, if the positive terminal plate 50a is attached to one longitudinal end of the battery module 50 and the negative terminal plate 50b is attached to the other longitudinal end of the battery module 50, the wiring such as bus bars and cables will be long. In contrast, if the positive terminal plate 50a and the negative terminal plate 50b are gathered together on one longitudinal end of the battery module 50, the wiring such as bus bars and cables can be shortened.

[0038] <Busbar Shape> As shown in FIG. 6 , the busbar group 59 includes a plurality of cell bus bars 81, a plurality of cell bus bars 82, a plurality of cell bus bars 83, and a plurality of cell bus bars 84. All of the plurality of cell bus bars 81 have the same shape, and all of the plurality of cell bus bars 82 have the same shape. All of the plurality of cell bus bars 83 have the same shape, and all of the plurality of cell bus bars 84 have the same shape. In this way, by forming the plurality of cell bus bars 81, the plurality of cell bus bars 82, the plurality of cell bus bars 83, and the plurality of cell bus bars 84 into the same shape, it is possible to reduce the number of types of bus bars that make up the busbar group 59. This reduces the cost of the battery module 50 and the cost of the battery pack 14.

[0039] In the illustrated example, all of the multiple cell bus bars 81 are formed in the same shape, all of the multiple cell bus bars 82 are formed in the same shape, all of the multiple cell bus bars 83 are formed in the same shape, and all of the multiple cell bus bars 84 are formed in the same shape, but this is not limited to this. For example, a configuration may be used in which at least any two of the multiple cell bus bars 81 are formed in the same shape, at least any two of the multiple cell bus bars 82 are formed in the same shape, at least any two of the multiple cell bus bars 83 are formed in the same shape, and at least any two of the multiple cell bus bars 84 are formed in the same shape. Even in this case, the number of types of bus bars that make up the bus bar group 59 can be reduced, thereby suppressing the cost of the battery pack 14.

[0040] As shown in FIG. 6 , the cell bus bar 81 and the cell bus bar 83 have the same shape. By forming the cell bus bar 81 and the cell bus bar 83 in this way, it is possible to reduce the number of types of bus bars that make up the bus bar group 59. Furthermore, the cell bus bar 82 and the cell bus bar 84 have the same shape. By forming the cell bus bar 82 and the cell bus bar 84 in this way, it is possible to reduce the number of types of bus bars that make up the bus bar group 59. This makes it possible to reduce the cost of the battery module 50, and therefore the cost of the battery pack 14.

[0041] As shown in FIG. 6 , the positive bus bar 65 and the negative bus bar 66 have the same shape. By forming the positive bus bar 65 and the negative bus bar 66 in this manner, the number of types of bus bars constituting the bus bar group 59 can be reduced. This reduces the cost of the battery module 50 and the cost of the battery pack 14. In the example shown in FIG. 3 , the positive component 86 consisting of the positive bus bar 65 and the positive terminal plate 50 a connected thereto, and the negative component 87 consisting of the negative bus bar 66 and the negative terminal plate 50 b connected thereto have the same shape, but this is not limited to this. In other words, it is sufficient that the shapes of the positive bus bar 65 and the negative bus bar 66 match each other, and the shapes of the positive terminal plate 50 a and the negative terminal plate 50 b may be different from each other.

[0042] 7, the cylindrical cells 55 adjacent to each other in the width direction D2 of the cell assembly 56 are arranged offset from each other in the longitudinal direction D1 of the cell assembly 56. This allows a large number of cylindrical cells 55 to be efficiently accommodated in the housing 54, thereby increasing the power storage capacity of the battery module 50. Furthermore, since the cylindrical cells 55 can be arranged close to each other, the bonding operation of connecting the cylindrical cells 55 to the bus bars 65 to 67 and 81 to 84 via bonding wires 85 is facilitated.

[0043] Furthermore, because the cylindrical cells 55, 55 adjacent to each other in the width direction D2 are arranged with a shift in the longitudinal direction D1, the connecting bar portions 81b, 82b, 83b, 84b of the cell bus bars 81, 82, 83, 84 extend in a direction inclined with respect to the longitudinal direction D1. This allows the cell bus bars 81, 82, 83, 84 to be appropriately arranged with respect to the electrode surfaces 57 of the cell assembly 56 without causing interference between the terminals 55a, 55b of the cylindrical cells 55 and the cell bus bars 81, 82, 83, 84.

[0044] <Modifications> Fig. 12 is a diagram showing a modification of the cell assembly and busbar group, and Fig. 13 is a diagram showing a modification of the busbar group. Fig. 14 is an enlarged view of area F14 shown in Fig. 12, Fig. 15 is an enlarged view of area F15 shown in Fig. 12, Fig. 16 is an enlarged view of area F16 shown in Fig. 12, and Fig. 17 is an enlarged view of area F17 shown in Fig. 12. Note that Figs. 12 and 13 show the same parts as Figs. 5 and 6 described above. In Fig. 12, parts and parts that are the same as those shown in Fig. 5 are designated by the same reference numerals, and their description will be omitted.

[0045] As shown in FIG. 12 , the cell assembly 90 includes a cell unit (first cell unit) 101 consisting of a plurality of cylindrical cells 55 and a cell unit (second cell unit) 102 consisting of a plurality of cylindrical cells 55. The cell unit 101 and the cell unit 102 are arranged adjacent to each other in the width direction D2 of the cell assembly 90. The cell unit 101 includes a plurality of cell groups (first cell group) 111 consisting of a plurality of cylindrical cells 55 and a plurality of cell groups (second cell group) 112 consisting of a plurality of cylindrical cells 55. The cell groups 111 and the cell groups 112 are arranged alternately in the longitudinal direction D1 of the cell assembly 90. Similarly, the cell unit 101 of the cell assembly 90 includes a plurality of cell groups (third cell group) 113 consisting of a plurality of cylindrical cells 55 and a plurality of cell groups (fourth cell group) 114 consisting of a plurality of cylindrical cells 55. The cell groups 113 and the cell groups 114 are arranged alternately in the longitudinal direction D1 of the cell assembly 90.

[0046] 12 , the bus bar group 92 facing the electrode surface 91 of the cell assembly 90 includes a positive bus bar 105 arranged at an end (first end) 90 a of the cell assembly 90 in the longitudinal direction D1, a negative bus bar 106 arranged at the end 90 a of the cell assembly 90 in the longitudinal direction D1, and an intermediate bus bar 107 arranged at an end (second end) 90 b of the cell assembly 90 in the longitudinal direction D1. The positive bus bar 105 includes a plate portion 105 a and a plurality of parallel bar portions 105 b extending linearly from the plate portion 105 a in the longitudinal direction D1. The negative bus bar 106 includes a plate portion 106 a and a plurality of parallel bar portions 106 b extending linearly from the plate portion 106 a in the longitudinal direction D1. Furthermore, the intermediate bus bar 107 has a plate portion 107a and a plurality of parallel bar portions 107b extending linearly from the plate portion 107a in the longitudinal direction D1.

[0047] The bus bar group 92 has a plurality of cell bus bars 121 and a plurality of cell bus bars 122 to connect the plurality of cylindrical cells 55 that make up the cell unit 101 to each other. That is, the bus bar group 92 has a plurality of cell bus bars (first bus bars) 121 that are arranged between the end 90a and the end 90b of the cell assembly 90. The bus bar group 92 also has a plurality of cell bus bars (second bus bars) 122 that are arranged between the end 90a and the end 90b of the cell assembly 90. The cell bus bars 121 and the cell bus bars 122 are arranged alternately in the longitudinal direction D1 of the cell assembly 90.

[0048] Similarly, the bus bar group 92 has a plurality of cell bus bars 123 and a plurality of cell bus bars 124 to connect the plurality of cylindrical cells 55 that make up the cell unit 102 to one another. That is, the bus bar group 92 has a plurality of cell bus bars (third bus bars) 123 that are arranged between the end 90a and the end 90b of the cell assembly 90. The bus bar group 92 also has a plurality of cell bus bars (fourth bus bars) 124 that are arranged between the end 90a and the end 90b of the cell assembly 90. The cell bus bars 123 and the cell bus bars 124 are arranged alternately in the longitudinal direction D1 of the cell assembly 90.

[0049] As shown in Fig. 13, the cell bus bar 121 includes a plurality of parallel bar portions (first parallel bar portions) 121a arranged parallel to one another and a plurality of connecting bar portions (first connecting bar portions) 121b connecting the parallel bar portions 121a to one another. The parallel bar portions 121a extend linearly in the longitudinal direction D1 of the cell assembly 90, while the connecting bar portions 121b extend curvedly in a direction inclined relative to the longitudinal direction D1. As shown in Fig. 14, the connecting bar portions 121b extend in a gently curved, approximately S-shaped manner so as to fit along the outer peripheries of adjacent cylindrical cells 55 in the width direction D2 of the cell assembly 90.

[0050] The cell bus bar 122 includes a plurality of parallel bar portions (second parallel bar portions) 122a arranged parallel to one another and a plurality of connecting bar portions (second connecting bar portions) 122b connecting the parallel bar portions 122a to one another. The parallel bar portions 122a extend linearly in the longitudinal direction D1 of the cell assembly 90, while the connecting bar portions 122b extend linearly in a direction inclined relative to the longitudinal direction D1. As shown in Figure 14, the connecting bar portions 122b extend in a gently curved, approximately S-shaped manner so as to fit along the outer peripheries of the cylindrical cells 55 adjacent to one another in the width direction D2 of the cell assembly 90.

[0051] The cell bus bar 123 includes a plurality of parallel bar portions (third parallel bar portions) 123a arranged parallel to one another and a plurality of connecting bar portions (third connecting bar portions) 123b connecting the parallel bar portions 123a to one another. The parallel bar portions 123a extend linearly in the longitudinal direction D1 of the cell assembly 90, while the connecting bar portions 123b extend curvedly in a direction inclined relative to the longitudinal direction D1. As shown in Figure 15, the connecting bar portions 123b extend in a gently curved, approximately S-shaped manner so as to fit along the outer peripheries of the cylindrical cells 55 adjacent to one another in the width direction D2 of the cell assembly 90.

[0052] The cell bus bar 124 includes a plurality of parallel bar portions (fourth parallel bar portions) 124a arranged parallel to one another and a plurality of connecting bar portions (fourth connecting bar portions) 124b connecting the parallel bar portions 124a to one another. The parallel bar portions 124a extend linearly in the longitudinal direction D1 of the cell assembly 90, while the connecting bar portions 124b extend linearly in a direction inclined relative to the longitudinal direction D1. As shown in Figure 15, the connecting bar portions 124b extend in a gently curved, approximately S-shaped manner so as to fit along the outer peripheries of the cylindrical cells 55 adjacent to one another in the width direction D2 of the cell assembly 90.

[0053] <Connection Structure of Cylindrical Cells (Enlarged View)> The connection structure of the cylindrical cells 55 using the cell bus bars 121, 122 will now be described. As shown in Fig. 14 , the parallel bar portions 121a of the cell bus bar 121 are connected, via bonding wires 85, to the positive terminals (positive electrodes) 55a of the three cylindrical cells 55 that make up the cell group 111, and are also connected to the negative terminals (negative electrodes) 55b of the three cylindrical cells 55 that make up the cell group 112. Furthermore, the parallel bar portions 122a of the cell bus bar 122 are connected, via bonding wires 85, to the positive terminals (positive electrodes) 55a of the three cylindrical cells 55 that make up the cell group 112, and are also connected to the negative terminals (negative electrodes) 55b of the three cylindrical cells 55 that make up the cell group 111.

[0054] The connection structure of the cylindrical cells 55 using the cell bus bars 123, 124 will now be described. As shown in Fig. 15 , the parallel bar portions 123a of the cell bus bar 123 are connected, via bonding wires 85, to the positive terminals (positive electrodes) 55a of the three cylindrical cells 55 that make up the cell group 113, and are also connected to the negative terminals (negative electrodes) 55b of the three cylindrical cells 55 that make up the cell group 114. Furthermore, the parallel bar portions 124a of the cell bus bar 124 are connected, via bonding wires 85, to the positive terminals (positive electrodes) 55a of the three cylindrical cells 55 that make up the cell group 114, and are also connected to the negative terminals (negative electrodes) 55b of the three cylindrical cells 55 that make up the cell group 113.

[0055] The connection structure of the cylindrical cells 55 using the positive bus bar 105 and the negative bus bar 106 will be described. As shown in Fig. 16 , the parallel bar portions 105b of the positive bus bar 105 are each connected via bonding wires 85 to the positive terminals (positive electrodes) 55a of the three cylindrical cells 55 that make up the cell group 111. The parallel bar portions 106b of the negative bus bar 106 are each connected via bonding wires 85 to the negative terminals (negative electrodes) 55b of the three cylindrical cells 55 that make up the cell group 114.

[0056] The following describes the connection structure of the cylindrical cells 55 using the intermediate bus bar 107. As shown in Fig. 17 , the parallel bar portions 107b of the intermediate bus bar 107 are connected, via bonding wires 85, to the negative terminals (negative electrodes) 55b of the three cylindrical cells 55 that make up the cell group 112, and to the positive terminals (positive electrodes) 55a of the three cylindrical cells 55 that make up the cell group 113.

[0057] 12 , an intermediate bus bar 107 is provided at the end 90b of the cell assembly 90, and this intermediate bus bar 107 connects the negative electrode of the cell unit 101 and the positive electrode of the cell unit 102 to each other. This allows the positive electrode of the cell unit 101 and the negative electrode of the cell unit 102 to be gathered at the end 90a of the cell assembly 90, and the positive electrode bus bar 105 and the negative electrode bus bar 106 to be gathered at the end 90a of the cell assembly 90. In other words, the positive electrode terminal plates 50a and the negative electrode terminal plates 50b of the battery module 50 can be gathered on one side in the longitudinal direction of the battery module 50, thereby simplifying the wiring of the battery module 50.

[0058] <Busbar Shape> As shown in Fig. 13 , all of the multiple cell bus bars 121 have the same shape as one another, and all of the multiple cell bus bars 122 have the same shape as one another. Furthermore, all of the multiple cell bus bars 123 have the same shape as one another, and all of the multiple cell bus bars 124 have the same shape as one another. Furthermore, the cell bus bars 121 and 123 have the same shape as one another, and the cell bus bars 122 and 124 have the same shape as one another. Furthermore, the positive electrode bus bar 105 and the negative electrode bus bar 106 have the same shape as one another. This allows the number of bus bars constituting the bus bar group 92 to be reduced, thereby reducing the cost of the battery module 50 and the cost of the battery pack 14.

[0059] Furthermore, because the cylindrical cells 55, 55 adjacent to each other in the width direction D2 are arranged with a staggered arrangement in the longitudinal direction D1, the connecting bar portions 121b, 122b, 123b, 124b of the cell bus bars 121, 122, 123, 124 extend in a direction inclined with respect to the longitudinal direction D1. This allows the cell bus bars 121, 122, 123, 124 to be appropriately arranged with respect to the electrode surfaces 91 of the cell assembly 90 without causing interference between the terminals 55a, 55b of the cylindrical cells 55 and the cell bus bars 121, 122, 123, 124.

[0060] <Other Modifications> The present disclosure is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit and scope of the present disclosure. In the illustrated example, the battery pack 14 is provided in an electric vehicle, but this is not limiting, and the battery pack 14 can also be used in other devices. Furthermore, as the cylindrical cells 55, not only batteries such as lithium-ion batteries can be used, but also storage cells such as capacitors can be used.

[0061] In the illustrated example, the positive bus bar 65 (105) and the negative bus bar 66 (106) have the same shape, but this is not limited to this and the positive bus bar 65 (105) and the negative bus bar 66 (106) may have different shapes. Furthermore, in the illustrated example, the cell bus bar 81 (121) and the cell bus bar 83 (123) have the same shape, but this is not limited to this and the cell bus bar 81 (121) and the cell bus bar 83 (123) may have different shapes. Furthermore, in the illustrated example, the cell bus bar 82 (122) and the cell bus bar 84 (124) have the same shape, but this is not limited to this and the cell bus bar 82 (122) and the cell bus bar 84 (124) may have different shapes.

[0062] 22, 23... Battery module (energy storage device), 50... Battery module (energy storage device), 55... Cylindrical cell, 55a... Positive terminal (positive electrode), 55b... Negative terminal (negative electrode), 56... Cell assembly, 56a... End (first end), 56b... End (second end), 57... Electrode surface, 59... Busbar group, 61... Cell unit (first cell unit), 62... Cell unit (second cell unit), 65... Positive busbar, 66... ​​Negative busbar, 67... Intermediate busbar, 71... Cell group (first cell group), 72... Cell group (second cell group), 73... Cell Group (third cell group), 74...cell group (fourth cell group), 81...cell bus bar (first bus bar), 81a...parallel bar portion (first parallel bar portion), 81b...connecting bar portion (first connecting bar portion), 82...cell bus bar (second bus bar), 82a...parallel bar portion (second parallel bar portion), 82b...connecting bar portion (second connecting bar portion), 83...cell bus bar (third bus bar), 83a...parallel bar portion (third parallel bar portion), 83b...connecting bar portion (third connecting bar portion), 84...cell bus bar (fourth bus bar), 84a...parallel bar portion (fourth parallel bar portion), 84 b...connecting bar portion (fourth connecting bar portion), 85...bonding wire, 90...cell assembly, 90a...end portion (first end portion), 90b...end portion (second end portion), 91...electrode surface, 92...busbar group, 101...cell unit (first cell unit), 102...cell unit (second cell unit), 105...positive bus bar, 106...negative bus bar, 107...intermediate bus bar, 111...cell group (first cell group), 112...cell group (second cell group), 113...cell group (third cell group), 114...cell group (fourth cell group), 121...cell bus bar (first bus bar), 121a...parallel bar portion (first parallel bar portion), 121b...connecting bar portion (first connecting bar portion), 122...cell bus bar (second bus bar), 122a...parallel bar portion (second parallel bar portion), 122b...connecting bar portion (second connecting bar portion), 123...cell bus bar (third bus bar), 123a...parallel bar portion (third parallel bar portion), 123b...connecting bar portion (third connecting bar portion), 124...cell bus bar (fourth bus bar), 124a...parallel bar portion (fourth parallel bar portion), 124b...connecting bar portion (fourth connecting bar portion), D1...longitudinal direction

Claims

1. An energy storage device comprising: a cell assembly comprising a first cell unit consisting of a plurality of cylindrical cells; and a second cell unit arranged adjacent to the first cell unit and consisting of a plurality of cylindrical cells; and a bus bar group arranged opposite electrode surfaces of the cell assembly and connecting the first cell unit and the second cell unit to each other, wherein the bus bar group comprises: a positive bus bar arranged at a first longitudinal end of the cell assembly and connected to the positive electrode of the first cell unit; a negative bus bar arranged at the first end of the cell assembly and connected to the negative electrode of the second cell unit; and an intermediate bus bar arranged at a second longitudinal end of the cell assembly and connecting the negative electrode of the first cell unit to the positive electrode of the second cell unit to each other.

2. An energy storage device according to claim 1, wherein the first cell unit comprises a plurality of first cell groups consisting of a plurality of the cylindrical cells and a plurality of second cell groups consisting of a plurality of the cylindrical cells, the first cell groups and the second cell groups being arranged alternately in the longitudinal direction of the cell assembly, the second cell unit comprises a plurality of third cell groups consisting of a plurality of the cylindrical cells and a plurality of fourth cell groups consisting of a plurality of the cylindrical cells, the third cell groups and the fourth cell groups being arranged alternately in the longitudinal direction of the cell assembly, the positive electrode bus bar is connected to the positive electrode of the first cell group, the negative electrode bus bar is connected to the negative electrode of the fourth cell group, and the intermediate bus bar is connected to the negative electrode of the second cell group and the positive electrode of the third cell group.

3. The energy storage device according to claim 1, wherein the first cell unit comprises a plurality of first cell groups consisting of a plurality of the cylindrical cells and a plurality of second cell groups consisting of a plurality of the cylindrical cells, the first cell groups and the second cell groups being alternately arranged in the longitudinal direction of the cell assembly, the second cell unit comprises a plurality of third cell groups consisting of a plurality of the cylindrical cells and a plurality of fourth cell groups consisting of a plurality of the cylindrical cells, the third cell groups and the fourth cell groups being alternately arranged in the longitudinal direction of the cell assembly, and the bus bar group comprises a plurality of first bus bars arranged between the first end and the second end of the cell assembly, connecting the positive electrodes of the first cell groups and the negative electrodes of the second cell groups to each other, and a plurality of second bus bars arranged between the first end and the second end of the cell assembly, connecting the positive electrodes of the second cell groups and the negative electrodes of the first cell groups to each other, a plurality of third bus bars arranged between the first end and the second end of the cell assembly, connecting positive electrodes of the third cell group and negative electrodes of the fourth cell group to each other; and a plurality of fourth bus bars arranged between the first end and the second end of the cell assembly, connecting positive electrodes of the fourth cell group and negative electrodes of the third cell group to each other.

4. The energy storage device according to claim 1, wherein the positive bus bar and the negative bus bar have the same shape.

5. The energy storage device according to claim 3, wherein the first bus bar and the third bus bar have the same shape.

6. The energy storage device according to claim 3, wherein the second bus bar and the fourth bus bar have the same shape.

7. An energy storage device according to claim 3, wherein the first bus bar comprises a plurality of first parallel bar sections arranged parallel to each other and connected to bonding wires, and a plurality of first connecting bar sections connecting the plurality of first parallel bar sections to each other; the second bus bar comprises a plurality of second parallel bar sections arranged parallel to each other and connected to bonding wires, and a plurality of second connecting bar sections connecting the plurality of second parallel bar sections to each other; the third bus bar comprises a plurality of third parallel bar sections arranged parallel to each other and connected to bonding wires, and a plurality of third connecting bar sections connecting the plurality of third parallel bar sections to each other; and the fourth bus bar comprises a plurality of fourth parallel bar sections arranged parallel to each other and connected to bonding wires, and a plurality of fourth connecting bar sections connecting the plurality of fourth parallel bar sections to each other.

8. An energy storage device according to claim 7, wherein the first parallel bar portion, the second parallel bar portion, the third parallel bar portion and the fourth parallel bar portion extend linearly in the longitudinal direction of the cell assembly, and the first connecting bar portion, the second connecting bar portion, the third connecting bar portion and the fourth connecting bar portion extend linearly in a direction inclined relative to the longitudinal direction of the cell assembly.

9. An energy storage device according to claim 7, wherein the first parallel bar portion, the second parallel bar portion, the third parallel bar portion and the fourth parallel bar portion extend linearly in the longitudinal direction of the cell assembly, and the first connecting bar portion, the second connecting bar portion, the third connecting bar portion and the fourth connecting bar portion extend curvedly in a direction inclined relative to the longitudinal direction of the cell assembly.

Images