Power storage device

Abstract

A power storage device according to the present invention has a cell assembly including a plurality of first cell groups and a plurality of second cell groups respectively comprising a plurality of cylindrical cells. The power storage device includes a busbar group that connects the first cell group and the second cell group to each other. The busbar group includes: a plurality of first busbars that connect the positive electrodes of the first cell group and the negative electrodes of the second cell group to each other; and a plurality of second busbars that connect the positive electrodes of the second cell group and the negative electrodes of the first cell group to each other. At least any two among the plurality of first busbars have the same shape as one another, and at least any two among the plurality of second busbars have the same shape as one another.

Description

Power storage device

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

[0002] Electric vehicles, hybrid vehicles, and the like have a battery pack as an electricity storage device including a battery module, a controller, etc. Furthermore, cylindrical cells are used as the multiple battery cells that make up the battery module (see Patent Document 1).

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

[0004] Incidentally, a plurality of cylindrical cells constituting a battery module are connected to each other via bus bars made of metal plates. A battery module incorporates a large number of cylindrical cells, and the cylindrical cells are typically connected to each other by combining bus bars of various shapes. However, combining bus bars of various shapes increases the number of bus bar types and the cost of the power storage device. Therefore, there is a demand for reducing the cost of the power storage device.

[0005] According to the present disclosure, an energy storage device includes a cell assembly including a plurality of first cell groups and a plurality of second cell groups, each of which includes a plurality of cylindrical cells. The energy storage device includes a bus bar group connecting the first cell groups and the second cell groups to each other. The bus bar group includes a plurality of first bus bars connecting positive electrodes of the first cell groups to negative electrodes of the second cell groups to each other, and a plurality of second bus bars connecting positive electrodes of the second cell groups to negative electrodes of the first cell groups to each other. At least two of the plurality of first bus bars have the same shape, and at least two of the plurality of second bus bars have the same shape.

[0006] According to the present disclosure, the cost of the power storage device can be reduced.

[0007] FIG. 1 is a diagram showing an example of a vehicle. FIG. 2 is a diagram showing an example of the configuration of a battery pack. FIG. 3 is an exploded perspective view showing a battery module. FIG. 4 is a diagram showing a cell assembly, an insulating plate, and a bus bar group from the direction of arrow A1 in FIG. 3. FIG. 5 is a diagram showing the bus bar group from the direction of arrow A1 in FIG. 3. FIG. 6 is an enlarged view of a range F6 shown in FIG. 4. FIG. 7 is a diagram showing a connection state of a cell group using a bus bar group. FIG. 8 is a diagram showing a modified example of a cell assembly and a bus bar group. FIG. 9 is a diagram showing a modified example of a bus bar group. FIG. 10 is an enlarged view of a range F10 shown in FIG. 8.

[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 again.

[0009] <Vehicle> FIG. 1 is a diagram showing an example of a vehicle 10. The vehicle 10 shown in FIG. 1 is equipped with 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 (electric storage device) 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 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 terminal block 25 via a module bus bar 31, and the negative terminal plate 23b of the battery module 23 is connected to the terminal block 25 via a module bus bar 32. The negative terminal plate 22b of the battery module 22 and the positive terminal plate 23a of the battery module 23 are connected to each other via a module bus bar 33. In the illustrated example, the battery pack 14 is provided with two battery modules 22, 23, but this is not limited thereto. The battery pack 14 may be provided with one battery module, or three or more battery modules. In the illustrated example, the battery modules 22, 23 are connected in series to each other, but this is not limited thereto. The battery modules 22, 23 may be connected in parallel to each other.

[0012] 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.

[0013] <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.

[0014] 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 view showing the cell assembly 56, insulating plate 58, and bus bar group 59 from the direction of arrow A1 in FIG. 3, and FIG. 5 is a view showing the bus bar group 59 from the direction of arrow A1 in FIG. 3. FIG. 6 is an enlarged view of a range F6 shown in FIG. 4. Similar to FIG. 3, FIGS. 4 and 5 also show both ends of the cell assembly 56 and bus bar group 59 and their vicinity.

[0015] As shown in FIG. 3 , the battery module 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, 71, and 72, each of which is made of a metal plate such as an aluminum alloy. The bus bar 65 is integrally provided with a positive terminal plate 50a, and the bus bar 66 is integrally provided with a negative terminal plate 50b.

[0016] 4, the cell assembly 56 has a plurality of cell groups (first cell groups) 61 each consisting of a plurality of cylindrical cells 55, and a plurality of cell groups (second cell groups) 62 each consisting of a plurality of cylindrical cells 55. The cell groups 61 and the cell groups 62 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 provided in the cell assembly 56.

[0017] 4 , the bus bar group 59 includes a positive bus bar 65 arranged at an end (first end) 56a of the cell assembly 56 in the longitudinal direction D1, and a negative bus bar 66 arranged at an end (second end) 56b of the cell assembly 56 in the longitudinal direction D1. The positive bus bar 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 of the cell assembly 56. The negative bus bar 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 of the cell assembly 56.

[0018] The bus bar group 59 has a plurality of cell bus bars (first bus bars) 71 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) 72 arranged between the end 56 a and the end 56 b of the cell assembly 56. These cell bus bars 71 and cell bus bars 72 are arranged alternately in the longitudinal direction D1 of the cell assembly 56.

[0019] As shown in Fig. 5, the cell bus bar 71 includes a plurality of parallel bar portions (first parallel bar portions) 71a arranged parallel to one another and a plurality of connecting bar portions (first connecting bar portions) 71b connecting the parallel bar portions 71a to one another. The parallel bar portions 71a extend linearly in the longitudinal direction D1 of the cell assembly 56, while the connecting bar portions 71b extend linearly in a direction inclined relative to the longitudinal direction D1. As shown in Fig. 6, the connecting bar portions 71b 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 71a of the cell bus bar 71 are connected to the positive electrode of the cell group 61 and the negative electrode of the cell group 62.

[0020] As shown in Fig. 5, the cell bus bar 72 includes a plurality of parallel bar portions (second parallel bar portions) 72a arranged parallel to one another and a plurality of connecting bar portions (second connecting bar portions) 72b connecting the parallel bar portions 72a to one another. The parallel bar portions 72a extend linearly in the longitudinal direction D1 of the cell assembly 56, while the connecting bar portions 72b extend linearly in a direction inclined relative to the longitudinal direction D1. As shown in Fig. 6, the connecting bar portions 72b 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 72a of the cell bus bar 72 are connected to the positive electrode of the cell group 62 and the negative electrode of the cell group 61.

[0021] As shown in the enlarged portion of Figure 6, each cylindrical cell 55 constituting the cell groups 61 and 62 has a positive terminal 55a located at the center of the cell end face and an annular negative terminal 55b arranged to surround the positive terminal 55a. Each of the parallel bar portions 71a of the cell bus bar 71 is connected via bonding wires 73 to the positive terminals (positive electrodes) 55a of the two cylindrical cells 55 constituting the cell group 61 and to the negative terminals (negative electrodes) 55b of the two cylindrical cells 55 constituting the cell group 62. Each of the parallel bar portions 72a of the cell bus bar 72 is connected via bonding wires 73 to the positive terminals (positive electrodes) 55a of the two cylindrical cells 55 constituting the cell group 62 and to the negative terminals (negative electrodes) 55b of the two cylindrical cells 55 constituting the cell group 61.

[0022] 7 is a diagram showing the connection state of the cell groups 61 and 62 by the bus bar group 59. As shown in Fig. 7, the positive bus bar 65 arranged at the end 56a of the cell assembly 56 is connected to the positive electrodes of the cylindrical cells 55 that make up the cell group 61. Furthermore, the negative bus bar 66 arranged at the end 56b of the cell assembly 56 is connected to the negative electrodes of the cylindrical cells 55 that make up the cell group 62.

[0023] 7 , a cell bus bar 71 and a cell bus bar 72 are arranged between end 56a and end 56b of cell assembly 56. Cell bus bar 71 is connected to the positive electrodes of cylindrical cells 55 that make up cell group 61 and the negative electrodes of cylindrical cells 55 that make up cell group 62. Cell bus bar 72 is connected to the positive electrodes of cylindrical cells 55 that make up cell group 62 and the negative electrodes of cylindrical cells 55 that make up cell group 61. In other words, the multiple cylindrical cells 55 that make up cell group 61 are connected in parallel, and the multiple cylindrical cells 55 that make up cell group 62 are connected in parallel. Cell group 61 and cell group 62 are connected in series.

[0024] <Busbar Shape> As shown in Fig. 5 , the busbar group 59 has a plurality of cell busbars 71 and a plurality of cell busbars 72. All of the plurality of cell busbars 71 have the same shape, and all of the plurality of cell busbars 72 have the same shape. By forming the plurality of cell busbars 71 and the plurality of cell busbars 72 in the same shape in this way, it is possible to reduce the number of types of busbars that make up the busbar group 59. This makes it possible to reduce the cost of the battery module 50 and the cost of the battery pack 14.

[0025] In the illustrated example, all of the multiple cell bus bars 71 are formed in the same shape, and all of the multiple cell bus bars 72 are formed in the same shape, but this is not limited thereto, and a configuration in which any two of the multiple cell bus bars 71 are formed in the same shape and any two of the multiple cell bus bars 72 are formed in the same shape may also be used. Even in this case, the number of types of bus bars that make up the bus bar group 59 can be reduced, thereby reducing the cost of the battery pack 14. In other words, in order to reduce the cost of the battery pack 14, it is sufficient to form at least any two of the multiple cell bus bars 71 in the same shape and at least any two of the multiple cell bus bars 72 in the same shape.

[0026] As shown in FIG. 5 , 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 74 consisting of the positive bus bar 65 and the positive terminal plate 50 a connected thereto, and the negative component 75 consisting of the negative bus bar 66 and the negative terminal plate 50 b connected thereto have the same shape, but this is not limiting. 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.

[0027] As shown by arrow X1 in Fig. 6 , 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 multiple cylindrical cells 55 can be arranged close to each other, the bonding operation of connecting the cylindrical cells 55 to the bus bars 65, 66, 71, and 72 via the bonding wires 73 becomes easier.

[0028] 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 71b, 72b of the cell bus bars 71, 72 extend in a direction inclined with respect to the longitudinal direction D1. This allows the cell bus bars 71, 72 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 71, 72.

[0029] <Modifications> Fig. 8 is a diagram showing a modification of the cell assembly and busbar group, and Fig. 9 is a diagram showing a modification of the busbar group. Fig. 10 is an enlarged view of an area F10 shown in Fig. 8. Note that Figs. 8 and 9 show the same parts as those shown in Figs. 4 and 5 above. In Figs. 8, 9, and 10, parts and parts that are the same as those shown in Figs. 4, 5, and 6 are designated by the same reference numerals, and their description will be omitted.

[0030] 8, the cell assembly 80 has a plurality of cell groups (first cell groups) 81 each consisting of a plurality of cylindrical cells 55, and a plurality of cell groups (second cell groups) 82 each consisting of a plurality of cylindrical cells 55. The cell groups 81 and the cell groups 82 are alternately arranged in the longitudinal direction D1 of the cell assembly 80.

[0031] 8 , the bus bar group 83 facing the electrode surface 80 c of the cell assembly 80 includes a positive bus bar 85 arranged at an end (first end) 80 a in the longitudinal direction D1 of the cell assembly 80, and a negative bus bar 86 arranged at an end (second end) 80 b in the longitudinal direction D1 of the cell assembly 80. The positive bus bar 85 includes a plate portion 85 a and a plurality of parallel bar portions 85 b extending linearly from the plate portion 85 a in the longitudinal direction D1 of the cell assembly 80. The negative bus bar 86 includes a plate portion 86 a and a plurality of parallel bar portions 86 b extending linearly from the plate portion 86 a in the longitudinal direction D1 of the cell assembly 80.

[0032] The bus bar group 83 has a plurality of cell bus bars (first bus bars) 91 arranged between the end 80a and the end 80b of the cell assembly 80. The bus bar group 83 also has a plurality of cell bus bars (second bus bars) 92 arranged between the end 80a and the end 80b of the cell assembly 80. These cell bus bars 91 and cell bus bars 92 are arranged alternately in the longitudinal direction D1 of the cell assembly 80.

[0033] As shown in Fig. 9, the cell bus bar 91 includes a plurality of parallel bar portions (first parallel bar portions) 91a arranged parallel to one another and a plurality of connecting bar portions (first connecting bar portions) 91b connecting the parallel bar portions 91a to one another. The parallel bar portions 91a extend linearly in the longitudinal direction D1 of the cell assembly 80, while the connecting bar portions 91b extend curvedly in a direction inclined relative to the longitudinal direction D1. As shown in Fig. 10, the connecting bar portions 91b 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 80.

[0034] As shown in Fig. 9, the cell bus bar 92 includes a plurality of parallel bar portions (second parallel bar portions) 92a arranged parallel to one another and a plurality of connecting bar portions (second connecting bar portions) 92b connecting the parallel bar portions 92a to one another. The parallel bar portions 92a extend linearly in the longitudinal direction D1 of the cell assembly 80, and the connecting bar portions 92b extend linearly in a direction inclined relative to the longitudinal direction D1. As shown in Fig. 10, the connecting bar portions 92b extend in a gently curved, approximately S-shaped manner so as to follow the outer peripheries of the cylindrical cells 55 adjacent to one another in the width direction D2 of the cell assembly 80.

[0035] 10 , the parallel bar portions 91 a of the cell bus bar 91 are connected, via bonding wires 93, to the positive terminals (positive electrodes) 55 a of the three cylindrical cells 55 that make up the cell group 81, and are also connected to the negative terminals (negative electrodes) 55 b of the three cylindrical cells 55 that make up the cell group 82. Furthermore, the parallel bar portions 92 a of the cell bus bar 92 are connected, via bonding wires 93, to the positive terminals (positive electrodes) 55 a of the three cylindrical cells 55 that make up the cell group 82, and are also connected to the negative terminals (negative electrodes) 55 b of the three cylindrical cells 55 that make up the cell group 81.

[0036] <Busbar Shape> As shown in FIG. 9 , the busbar group 83 includes a plurality of cell busbars 91 and a plurality of cell busbars 92. All of the plurality of cell busbars 91 have the same shape, and all of the plurality of cell busbars 92 have the same shape. By forming the plurality of cell busbars 91 and the plurality of cell busbars 92 in the same shape in this way, the number of types of busbars constituting the busbar group 83 can be reduced. This reduces the cost of the battery module 50 and the cost of the battery pack 14. As described above, in order to reduce the cost of the battery pack 14, it is sufficient that at least any two of the plurality of cell busbars 91 are formed in the same shape and at least any two of the plurality of cell busbars 92 are formed in the same shape.

[0037] 9 , the positive bus bar 85 and the negative bus bar 86 have the same shape. By forming the positive bus bar 85 and the negative bus bar 86 in this way to the same shape, it is possible to reduce the number of types of bus bars that make up the bus bar group 83. This makes it possible to reduce the cost of the battery module 50 and the cost of the battery pack 14.

[0038] 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 91b, 92b of the cell bus bars 91, 92 extend in a direction inclined with respect to the longitudinal direction D1. This allows the cell bus bars 91, 92 to be appropriately arranged with respect to the electrode surfaces 80c of the cell assembly 80 without causing interference between the terminals 55a, 55b of the cylindrical cells 55 and the cell bus bars 91, 92.

[0039] <Other Modifications> The present disclosure is not limited to the above-described embodiment and may be modified in various ways 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 limited thereto, and the battery pack 14 may also be used in other devices. Furthermore, as the cylindrical cells 55, not only batteries such as lithium-ion batteries but also storage cells such as capacitors may be used. In the illustrated example, the positive bus bar 65 (85) and the negative bus bar 66 (86) have the same shape, but this is not limited thereto, and the positive bus bar 65 (85) and the negative bus bar 66 (86) may have different shapes.

[0040] 14... Battery pack (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... Bus bar group, 61... Cell group (first cell group), 62... Cell group (second cell group), 65... Positive electrode bus bar, 66... ​​Negative electrode bus bar, 71... Cell bus bar (first bus bar), 71a... Parallel bar portion (first parallel bar portion), 71b... Connecting bar portion (first connecting bar portion), 72... Cell bus bar (second bus bar), 72a... Parallel bar portion (second parallel bar portion), 72b... Connecting bar portion ( second connecting bar portion), 73...bonding wire, 80...cell assembly, 80a...end (first end), 80b...end (second end), 80c...electrode surface, 81...cell group (first cell group), 82...cell group (second cell group), 83...bus bar group, 85...positive bus bar, 86...negative bus bar, 91...cell bus bar (first bus bar), 91a...parallel bar portion (first parallel bar portion), 91b...connecting bar portion (first connecting bar portion), 92...cell bus bar (second bus bar), 92a...parallel bar portion (second parallel bar portion), 92b...connecting bar portion (second connecting bar portion), 93...bonding wire, D1...longitudinal direction

Claims

1. An energy storage device comprising: a cell assembly comprising a plurality of first cell groups each consisting of a plurality of cylindrical cells; and a plurality of second cell groups each consisting of a plurality of cylindrical cells; and a bus bar group arranged opposite to the electrode surfaces of the cell assembly and connecting the first cell group and the second cell group to each other, wherein the first cell group and the second cell group are arranged alternately in the longitudinal direction of the cell assembly, and the bus bar group comprises a plurality of first bus bars connecting positive electrodes of the first cell group to negative electrodes of the second cell group to each other, and a plurality of second bus bars connecting positive electrodes of the second cell group to negative electrodes of the first cell group to each other, wherein at least any two of the plurality of first bus bars have the same shape as each other, and at least any two of the plurality of second bus bars have the same shape as each other.

2. The energy storage device according to claim 1, wherein all of the plurality of first bus bars have the same shape as one another, and all of the plurality of second bus bars have the same shape as one another.

3. An energy storage device according to claim 1, 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 group; and a negative bus bar arranged at a second longitudinal end of the cell assembly and connected to the negative electrode of the second cell group, wherein the positive bus bar and the negative bus bar have the same shape.

4. An energy storage device according to claim 1, 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, and 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.

5. An energy storage device according to claim 4, wherein the first parallel bar portion and the second parallel bar portion extend linearly in the longitudinal direction of the cell assembly, and the first connecting bar portion and the second connecting bar portion extend linearly in a direction inclined relative to the longitudinal direction of the cell assembly.

6. An energy storage device according to claim 4, wherein the first parallel bar portion and the second parallel bar portion extend linearly in the longitudinal direction of the cell assembly, and the first connecting bar portion and the second connecting bar portion extend curvedly in a direction inclined relative to the longitudinal direction of the cell assembly.

Images