JP7532066B2 - Power supply device, vehicle equipped with same, and power storage device - Google Patents

Description

This disclosure relates to a power supply device, a vehicle equipped with the same, and a power storage device.

Power supply devices such as battery modules and battery packs that have multiple battery cells are used as power sources for vehicles such as hybrid cars and electric cars, and as power sources for factory and home power storage systems (see, for example, Patent Document 1).

Such a power supply device has a plurality of stacked battery cells that can be charged and discharged. For example, as shown in the schematic cross-sectional view of FIG. 19, a power supply device 900 has end plates 903 arranged on both end faces of a battery stack 910 in which rectangular exterior can battery cells 901 are stacked, and the end plates 903 are fastened together with bind bars 904. In addition, the rectangular battery cells 901 have positive and negative electrode terminals 902 spaced apart on their top surfaces. The electrode terminals 902 of adjacent battery cells 901 are connected by bus bars 940.

Battery stacks, which are made by stacking battery cells, have different stacking thicknesses even when the number of cells is the same, due to manufacturing tolerances, etc. Conventionally, the battery stack was fastened by pressing both end faces until the stack length reached a specified dimension. After fastening, the electrode terminals of the battery cells were welded to bus bars to electrically connect them.

With this method, the pressing pressure varies depending on the thickness of the battery stack. In order to ensure the minimum pressure that can fix the battery stack within a certain dimension and to deal with excessive pressure due to variations in the battery stack, it is necessary to use high-strength materials for the end plates that cover the ends of the battery stack, which leads to a heavy product and high costs. Therefore, it is thought that the variation in pressing pressure can be reduced by adding an elastic body that adjusts the pressing pressure between the battery stack and the end plates.

However, this method results in variation in the stack length of the battery stack. As a result, a new problem arises in that the welding positions of the bus bars to be welded to the electrodes of the battery cells differ for each battery stack.

Patent No. 6344362

One of the objectives of one aspect of the present invention is to provide a power supply device that allows for positioning when welding electrode terminals to bus bars in a battery stack in which multiple battery cells are stacked, and a vehicle and a power storage device that are equipped with the same.

A power supply device according to one aspect of the present invention includes a battery stack in which multiple battery cells having electrode terminals on the upper surface of an outer can are stacked, multiple insulating spacers having insulating properties interposed between the multiple battery cells, end plates covering the end faces of the battery stack, fastening members for fastening the battery stack, and multiple bus bars connecting the electrode terminals of adjacent battery cells, and a positioning mechanism is provided between the bus bars connecting the electrode terminals between the adjacent battery cells and the insulating spacers interposed between the battery cells on the underside of the bus bars.

In a power supply device according to one aspect of the present invention, the insulating spacer can be used to position the busbar, making it easier to determine the welding positions for welding the busbar to the electrode terminal of each battery cell.

1 is a perspective view showing a power supply device according to a first embodiment of the present invention. FIG. 2 is an exploded perspective view of the power supply device shown in FIG. 1 . FIG. 2 is an enlarged perspective view showing an electrode terminal portion of the power supply device of FIG. 1 . FIG. 4 is an exploded perspective view of FIG. 3 . 5A to 5C are schematic cross-sectional views showing a state in which even when the same number of battery cells, each having individual differences in thickness, are stacked, there is variation in the stack length of the power supply device. 1 is a schematic cross-sectional view showing a power supply device including insulating spacers of different thicknesses. FIG. 1 is a schematic cross-sectional view showing a power supply device including an elastic body. 1 is a schematic cross-sectional view with an enlarged view of a main portion showing how electrode terminals and bus bars are positioned in a power supply device in which the electrode terminals are screw terminals; FIG. 13 is an exploded perspective view showing a positioning mechanism according to a modified example. FIG. 13 is an exploded perspective view showing a positioning mechanism according to another modified example. FIG. 13 is an exploded perspective view showing a positioning mechanism according to still another modified example. FIG. 11 is a perspective view showing a power supply device according to a second embodiment of the present invention. FIG. 14 is an exploded perspective view of the power supply device shown in FIG. 13. FIG. 14 is an enlarged perspective view showing an electrode terminal portion of the power supply device of FIG. 13. FIG. 16 is an exploded perspective view of FIG. 1 is a block diagram showing an example of a power supply device mounted on a hybrid vehicle that runs on an engine and a motor. FIG. 1 is a block diagram showing an example in which a power supply device is mounted on an electric vehicle that runs only on a motor. FIG. 11 is a block diagram showing an example of application to a power supply device for power storage. FIG. 13 is an exploded perspective view showing a conventional power supply device.

An embodiment of the present invention may be characterized by the following configuration:

In addition to the above configuration, the power supply device according to one embodiment of the present invention has a positioning mechanism that includes an opening in the bus bar and a protrusion formed on the insulating spacer that is inserted into the opening. With the above configuration, the protrusion of the insulating spacer can be inserted into the opening of the bus bar, making it easier to position the welding position of the bus bar for each battery cell.

In addition to any of the above configurations, a power supply device according to another embodiment of the present invention further includes a busbar holder that holds the busbars, and the busbars are positioned by the positioning mechanism via the busbar holder. This configuration makes it possible to position the busbars using the insulating spacer and the busbar holder, making it easier to determine the welding positions for welding the busbars to the electrode terminals of each battery cell.

In addition to any of the configurations described above, a power supply device according to another embodiment of the present invention has a positioning mechanism that includes an opening in the bus bar holder and a protrusion formed on the insulating spacer that is inserted into the opening. With the above configuration, the protrusion of the insulating spacer can be inserted into the opening of the bus bar holder, making it easier to position the welding position of the bus bar for each battery cell.

Furthermore, in addition to any of the above configurations, a power supply device according to another embodiment of the present invention further includes an elastic body that adjusts the thickness of the pressure applied between the end plates before they are pressed together.

Furthermore, in a power supply device according to another embodiment of the present invention, in addition to any of the above configurations, the electrode terminals protrude from the top surface of the outer casing by 5 mm or less. With the above configuration, it is possible to position the electrode terminals even for battery cells that have a small protrusion amount and are difficult to mechanically position using only the electrode terminals.

An electric vehicle according to another embodiment of the present invention includes any of the power supply devices described above, a motor for driving that receives power from the power supply device, a vehicle body that is equipped with the power supply device and the motor, and wheels that are driven by the motor to drive the vehicle body.

Furthermore, a power storage device according to another embodiment of the present invention includes any of the power supply devices described above and a power supply controller that controls charging and discharging of the power supply device, and the power supply controller enables charging of the battery cells using external power and controls charging of the battery cells.

The following describes an embodiment of the present invention based on the drawings. However, the following embodiment is an example for embodying the technical idea of the present invention, and the present invention is not limited to the following. In addition, this specification does not specify the members shown in the claims to the members of the embodiment. In particular, the dimensions, materials, shapes, and relative positions of the components described in the embodiments are not intended to limit the scope of the present invention, and are merely explanatory examples, unless otherwise specified. Note that the size and positional relationship of the components shown in each drawing may be exaggerated to clarify the explanation. Furthermore, in the following explanation, the same name and symbol indicate the same or similar components, and detailed explanations will be omitted as appropriate. Furthermore, each element constituting the present invention may be configured with the same material so that multiple elements are shared by one material, or conversely, the function of one material can be shared by multiple materials. In addition, the contents described in some examples and embodiments may be applicable to other examples and embodiments.

The power supply device according to the embodiment is used for various purposes, such as a power supply mounted on an electric vehicle such as a hybrid car or an electric car to supply power to a driving motor, a power supply for storing power generated by natural energy such as solar power generation or wind power generation, or a power supply for storing late-night power, and is particularly used as a power supply suitable for large power and large current applications. In the following example, an embodiment applied to a power supply device for driving an electric vehicle will be described.
[Embodiment 1]

A power supply device 100 according to a first embodiment of the present invention is shown in Figs. 1 and 2. In these figures, Fig. 1 shows a perspective view of the power supply device 100 according to the first embodiment, and Fig. 2 shows an exploded perspective view of the power supply device 100 shown in Fig. 1.

The power supply device 100 shown in these figures comprises a battery stack 10 in which multiple battery cells 1 are stacked with insulating spacers 16 between them, a pair of end plates 20 covering both side edges of the battery stack 10, multiple fastening members 15 fastening the end plates 20 together, and a bus bar 40 provided on the upper surface of the battery stack 10.

The fastening members 15 are formed in a plate shape that extends along the stacking direction of the multiple battery cells 1. The fastening members 15 are disposed on opposing side surfaces of the battery stack 10 and fasten the end plates 20 together.
(Battery stack 10)

As shown in FIG. 2 , the battery stack 10 includes a plurality of battery cells 1 each having positive and negative electrode terminals 2, and bus bars 40 that are connected to the electrode terminals 2 of the plurality of battery cells 1 and connect the plurality of battery cells 1 in parallel and in series. The plurality of battery cells 1 are connected in parallel and in series via these bus bars 40. The battery cells 1 are secondary batteries that can be charged and discharged. In the power supply device 100, a plurality of battery cells 1 are connected in parallel to form parallel battery groups, and a plurality of parallel battery groups are connected in series to connect a large number of battery cells 1 in parallel and in series. The power supply device 100 shown in FIG. 2 stacks a plurality of battery cells 1 to form the battery stack 10. A pair of end plates 20 are also arranged on both end faces of the battery stack 10. Ends of fastening members 15 are fixed to the end plates 20 to fix the stacked battery cells 1 in a pressed state.
(Battery cell 1)

As shown in FIG. 2, the battery cells 1 are rectangular batteries that are wider than their thickness, in other words thinner than their width, and are stacked in the thickness direction to form a battery stack 10. The battery cells 1 can be, for example, lithium-ion secondary batteries. The battery cells can also be any rechargeable secondary battery, such as nickel-metal hydride batteries or nickel-cadmium batteries. The battery cells 1 contain positive and negative electrode plates together with an electrolyte in an outer can 1a with a sealed structure. The outer can 1a is formed by pressing a metal plate such as aluminum or an aluminum alloy into a rectangular shape, and the opening is airtightly sealed with a sealing plate 1b. The sealing plate 1b is made of the same aluminum or aluminum alloy as the rectangular outer can 1a, and has positive and negative electrode terminals 2 fixed to both ends. Furthermore, the sealing plate 1b has a gas exhaust valve 1c between the positive and negative electrode terminals 2, which is a safety valve that opens in response to pressure changes inside the battery cells 1.

A plurality of battery cells 1 are stacked such that the thickness direction of each battery cell 1 is the stacking direction to form a battery stack 10. In this case, by stacking a larger number of battery cells than usual, it is possible to increase the output of the battery stack 10. In such a case, the battery stack 10 becomes elongated in the stacking direction. The battery cells 1 are stacked to form the battery stack 10 with the terminal surfaces 1X, on which the positive and negative electrode terminals 2 are provided, arranged on the same plane. The upper surface of the battery stack 10 is the surface on which the gas exhaust valves 1c of the plurality of battery cells 1 are provided.
(Electrode terminal 2)

As shown in FIG. 2 etc., the battery cell 1 has a terminal surface 1X formed by the sealing plate 1b, which is the top surface, and positive and negative electrode terminals 2 are fixed to both ends of this terminal surface 1X. The electrode terminals 2 have cylindrical protrusions. However, the protrusions do not necessarily have to be cylindrical, and can also be polygonal or elliptical.

The positions of the positive and negative electrode terminals 2 fixed to the sealing plate 1b of the battery cell 1 are such that the positive and negative electrodes are symmetrical. As a result, as shown in FIG. 2, the battery cells 1 are stacked in a reversed state, and adjacent positive and negative electrode terminals 2 that are close to each other are connected by a bus bar 40, so that adjacent battery cells 1 can be connected in series. Note that the present invention does not specify the number of battery cells that make up the battery stack and their connection state. The number of battery cells that make up the battery stack and their connection state can be changed in various ways, including other embodiments described below.

Multiple battery cells 1 are stacked such that the thickness direction of each battery cell 1 is the stacking direction to form a battery stack 10. In the battery stack 10, multiple battery cells 1 are stacked such that terminal surfaces 1X on which positive and negative electrode terminals 2 are provided, or sealing plates 1b in Fig. 2, are flush with each other. As shown in the enlarged perspective view of Fig. 3, adjacent electrode terminals 2 on both sides of the battery stack 10 are joined by metal bus bars 40 to connect the battery cells 1 in series.
(Bus bar 40)

The bus bar 40 has both ends connected to the positive and negative electrode terminals 2, connecting the battery cells 1 in series or in parallel. The power supply device 100 can increase the output voltage by connecting the battery cells 1 in series, and can increase the output voltage and output current by connecting the battery cells 1 in series and in parallel.

As shown in the enlarged exploded perspective view of FIG. 4, the positive and negative electrode terminals 2 of the battery cell 1 have a terminal block having a joint surface 2B and a protrusion 2A protruding from the joint surface 2B. The joint surface 2B is flat and parallel to the surface of the sealing plate 12. The protrusion 2A is provided in the center of the joint surface 2B. The electrode terminal 2 shown in FIG. 3 has a cylindrical protrusion 2A. However, the protrusion does not necessarily have to be cylindrical, and can also be a polygonal or elliptical cylinder, although this is not shown.

The busbar 40 has opening windows 62 at both ends so that it can be guided over the electrode terminal 2, and each opening window 62 guides the protruding portion 2A of the electrode terminal 2 of the adjacent battery cell 1. In the busbar 40 of Figs. 3 and 4, the opening windows 62 are through holes into which the protruding portion 2A is inserted. The opening windows 62 have an inner diameter that can guide the protruding portion 2A of the electrode terminal 2. Note that the opening windows of the busbar do not necessarily have to be through holes, and may have any shape that allows the positioning of the busbar using the protruding portion 2A of the electrode terminal 2. For example, the opening windows can be cut out by cutting out a part of the busbar.

As shown in Figs. 3 and 4, the bus bar 40 has a first connection portion 41, a second connection portion 51, and a connection portion 49 that connects them. These members are integrally formed by bending a metal plate or the like. The bus bar 40 is also made of a material with excellent electrical conductivity, preferably made of aluminum, copper, or the like.

The first connection portion 41 is connected to the electrode terminal 2 of one battery cell (on the left side in FIG. 3, etc.). The second connection portion 51 is connected to the electrode terminal 2 of the other battery cell (on the right side in FIG. 3, etc.). The first connection portion 41 and the second connection portion 51 are adjacent and substantially parallel to each other. This allows the adjacent electrode terminals 2 of the battery cell assembly, which are stacked so that the sealing plates are substantially flush with each other, to be connected to each other. The first connection portion 41 and the second connection portion 51 also have opening windows 62. The electrode terminal 2 is exposed through the opening windows 62.

The first connection portion 41 and the second connection portion 51 are connected via a connecting portion 49. The connecting portion 49 includes a first bent portion 43, a first intermediate portion 45, a second bent portion 53, a second intermediate portion 55, and a third bent portion 47. The first connection portion 41 and the first intermediate portion 45 are connected via the first bent portion 43. The second connection portion 51 and the second intermediate portion 55 are connected via the second bent portion 53. The first intermediate portion 45 and the second intermediate portion 55 are connected via the third bent portion 47.

The first bent portion 43 is bent from the first connection portion 41 at the first connection bend region 42, and is further bent between the first intermediate portion 45 and the first intermediate bend region 44. Preferably, the first connection bend region 42 between the first bend portion 43 and the first connection portion 41, and the first intermediate bend region 44 between the first bend portion 43 and the first intermediate portion 45 are bent at approximately right angles, so that the first connection portion 41, the first bent portion 43, and the first intermediate portion 45 are configured in a stepped shape. The first connection portion 41, the first bent portion 43, and the first intermediate portion 45 are configured by bending a single metal plate, and only the first connection portion 41 is fixed to the battery cell 1, while the first intermediate portion 45 is not fixed and is floating relative to the battery cell 1. As a result, even if the distance between the first connection portion 41 and the first intermediate portion 45 changes relative to one another, the first connection bending region 42 and the first intermediate bending region 44 of the first bending portion 43 bend and deform, absorbing any misalignment of the battery cell 1.

Similarly, the second bent portion 53 is bent from the second connection portion 51 at the second connection bend region 52, and is further bent between the second intermediate portion 55 and the second intermediate portion 54. Preferably, the second connection bend region 52 between the second bend portion 53 and the second connection portion 51, and the second intermediate bend region 54 between the second bend portion 53 and the second intermediate portion 55 are bent at approximately right angles, so that the second connection portion 51, the second bend portion 53, and the second intermediate portion 55 are configured in a step-like shape. These second connection portion 51, the second bend portion 53, and the second intermediate portion 55 are also configured from a single metal plate, and the second connection portion 51 side is fixed to the battery cell 1, while the second intermediate portion 55 is not fixed to the battery cell 1, so that the change in the relative distance between the second connection portion 51 and the second intermediate portion 55 can be absorbed by the second connection bend region 52 and the second intermediate bend region 54 of the second bend portion 53.

Furthermore, the first intermediate portion 45 and the second intermediate portion 55 are connected via a third bent portion 47. Specifically, the first intermediate portion 45 and the third bent portion 47 are connected via a third intermediate bent region 46, and the second intermediate portion 55 and the third bent portion 47 are connected via a fourth intermediate bent region 56. The third bent portion 47 is also preferably formed by bending the same material as the first intermediate portion 45 and the second intermediate portion 55, for example, a metal plate. Furthermore, the third bent portion 47 is formed in a U-shape in vertical cross section, and deformation of this portion can absorb any relative change in the distance between the first intermediate portion 45 and the second intermediate portion 55. Note that the vertical cross section shape of the third bent portion is not limited to a U-shape, and may be formed, for example, in an inverted mountain shape.

The first intermediate portion 45 and the first connecting portion 41, and the second intermediate portion 55 and the second connecting portion 51 are configured to be approximately parallel to each other. The first intermediate portion 45 and the second intermediate portion 55 are configured to be approximately parallel to each other, preferably on approximately the same plane. The first intermediate portion 45 is approximately rectangular in plan view, and the first connecting bend region 42 and the third intermediate bend region 46 are provided on adjacent sides at approximately right angles. Similarly, the second intermediate portion 55 is also approximately rectangular, and the second connecting bend region 52 and the fourth intermediate bend region 56 are provided on adjacent sides at approximately right angles. As a result, as shown in FIG. 3, etc., even if the distance between the first connecting portion 41 and the second connecting portion 51 changes relatively in the X-axis direction, this can be absorbed by the deformation of the third bend portion 47. Furthermore, the relative change in the Y-axis direction can be absorbed by the deformation of the first bend portion 43 and the second bend portion 53. Furthermore, the first bent portion 43 and the second bent portion 53 can also absorb relative changes in the Z-axis direction by deforming. In this way, the connecting portion 49, which is composed of the first bent portion 43, the first intermediate portion 45, the second bent portion 53, the second intermediate portion 55, and the third bent portion 47, can absorb changes in the relative distance between the first connecting portion 41 and the second connecting portion 51 in any of the X, Y, and Z directions. As a result, problems such as damage, breakage, and peeling of the welded portion between the electrode terminal 2 and the bus bar 40 due to load being applied to the welded portion due to relative displacement between the first connecting portion 41 and the second connecting portion 51 can be avoided.

As described above, by providing the connecting portion 49 connecting the first connecting portion 41 and the second connecting portion 51 with a buffer mechanism that is deformable in the XYZ directions, it is possible to absorb the tolerances of the battery cells during manufacturing and assembly. Even when the power supply device 100 is in use, even if the relative positions of the first connecting portion 41 and the second connecting portion 51 are shifted due to expansion caused by charging and discharging the battery cells or external forces such as shock or vibration, this can be absorbed by the buffer mechanism of the connecting portion 49, thereby preventing a situation in which a load is directly applied to the first connecting portion 41 or the second connecting portion 51, causing damage, breakage, or peeling, and improving the reliability of the connection between the battery cells.

The intermediate section can also be used as a detection terminal for the intermediate potential. In particular, when a lithium-ion secondary battery is used as a battery cell, the intermediate potential is detected in order to accurately manage the state of the battery, and therefore it is necessary to connect an intermediate potential detection terminal for detecting the intermediate potential. For this reason, the intermediate section having a shock absorbing mechanism can also be used as a member for connecting such an intermediate potential detection terminal.

Furthermore, the busbar 40 has a joint area for laser welding with the electrode terminal 2 of the battery cell 1. Specifically, the first connection portion 41 and the second connection portion 51 each have a thin-walled area 61 that is partially thinner than the other areas. A partially opened opening window 62 is formed in a part of the thin-walled area 61. When laser welding, the thin-walled area 61, which is arranged overlapping and in close contact with the joint surface 2B of the electrode terminal 2, is irradiated with laser light from above, penetrating the thin-walled area 61 and melting it together with the joint surface 2B for welding. At this time, it is necessary to accurately position the busbar 40 and the electrode terminal 2. Therefore, the protruding portion 2A of the electrode terminal 2 is exposed from the opening window 62, and this is used as a guide for relative positioning of the busbar 40 and the electrode terminal 2. It can also be used as a positioning device for controlling the welding position to which the laser light is irradiated. For example, the protruding portion 2A of the electrode terminal 2 exposed from the opening window 62 is detected by image processing, and the scanning position of the laser light is controlled based on this position. As a result, a joint is formed between the bus bar 40 and the terminal block of the electrode terminal 2 .
(Insulating spacer 16)

In the battery stack 10, insulating spacers 16 are interposed between adjacent stacked battery cells 1. The insulating spacers 16 are made of an insulating material such as resin in the form of a thin plate or sheet. The insulating spacers 16 are plate-shaped and have a size approximately equal to the size of the opposing surfaces of the battery cells 1. The insulating spacers 16 are stacked between adjacent battery cells 1 to insulate the adjacent battery cells 1 from each other. Note that as the spacer to be placed between adjacent battery cells, a spacer having a shape that forms a flow path for cooling gas between the battery cell and the spacer can also be used. The surface of the battery cell can also be covered with an insulating material. For example, the surface of the exterior can excluding the electrode terminal portion of the battery cell can be covered with a shrink film such as PET resin.

Furthermore, the power supply device 100 shown in FIG. 2 has end plates 20 arranged on both end faces of the battery stack 10. End surface spacers 17 may be interposed between the end plates 20 and the battery stack 10 to insulate them. The end surface spacers 17 may also be made in the form of thin plates or sheets using an insulating material such as resin.

In the power supply device 100 of the first embodiment, a battery stack 10 is formed in which a plurality of battery cells 1 are stacked on top of each other, and the electrode terminals 2 of adjacent battery cells 1 are connected to each other by bus bars 40, thereby connecting the plurality of battery cells 1 in parallel and in series.
(End plate 20)

2, the end plates 20 are arranged on both ends of the battery stack 10 and are fastened via a pair of left and right fastening members 15 arranged along both side surfaces of the battery stack 10. The end plates 20 are located on the outsides of the end spacers 17, at both ends of the battery stack 10 in the stacking direction of the battery cells 1, and sandwich the battery stack 10 from both ends.
(Fastening member 15)

Both ends of the fastening member 15 are fixed to the end plates 20 arranged on both end faces of the battery stack 10. The end plates 20 are fixed with a plurality of fastening members 15, thereby fastening the battery stack 10 in the stacking direction. As shown in FIG. 2 etc., each fastening member 15 is made of metal with a predetermined width and thickness that fits along the side of the battery stack 10, and is arranged opposite both side faces of the battery stack 10. The fastening members 15 can be made of a metal plate such as iron, preferably a steel plate. The fastening members 15 made of metal plate are bent by press molding or the like to form a predetermined shape.

The fastening member 15 is formed by bending the top and bottom of the plate-shaped fastening main surface 15a into a U-shape to form bent pieces 15d. The top and bottom bent pieces 15d cover the top and bottom surfaces of the battery stack 10 from the corners on the left and right sides of the battery stack 10. The fastening member 15 is fixed to the outer periphery of the end plate 20 by screwing bolts 15f into multiple fastening screw holes opened in the fastening main surface 15a. Note that the fastening main surface 15a and the end plate 20 are not necessarily fixed to each other by screwing using bolts, but may be fixed by pins, rivets, etc.

The power supply device 100, in which many battery cells 1 are stacked, is configured to restrain the multiple battery cells 1 by connecting end plates 20 arranged on both ends of a battery stack 10 consisting of the multiple battery cells 1 with fastening members 15. By restraining the multiple battery cells 1 via the end plates 20 and fastening members 15, which have high rigidity, it is possible to suppress the expansion, deformation, relative movement, and malfunction due to vibration of the battery cells 1 that accompanies charging/discharging and deterioration.
(Insulating sheet 30)

An insulating sheet 30 is interposed between the fastening member 15 and the battery stack 10. The insulating sheet 30 is made of an insulating material, such as resin, and insulates the metal fastening member 15 from the battery cell 1. The insulating sheet 30 shown in FIG. 2 and other figures is made of a flat plate 31 that covers the side of the battery stack 10, and folded covering parts 32 provided above and below the flat plate 31. The folded covering part 32 is folded back after being folded from the flat plate 31 into a U-shape so as to cover the folded piece 15d of the fastening member 15. In this way, the folded piece 15d is covered from the top to the side and bottom with the insulating folded covering part, thereby preventing unintended electrical conduction between the battery cell 1 and the fastening member 15.

The folded pieces 15d also press against the top and bottom surfaces of the battery cells 1 of the battery stack 10 via the folded covering parts 32. This allows each battery cell 1 to be pressed from above and below by the folded pieces 15d, holding it in the height direction, and keeping each battery cell 1 from shifting in position in the vertical direction even if vibrations, shocks, etc. are applied to the battery stack 10.

Note that an insulating sheet may be unnecessary if the battery stack or the surface of the battery stack is insulated, for example, if the battery cells are housed in an insulating case or covered with a resin heat-shrinkable film, or if the surfaces of the fastening members are coated with an insulating paint or coating, or if the fastening members are made of an insulating material, etc. Also, for the insulating sheet 30, if there is no need to consider insulation from the folded pieces 15d of the fastening members 15 on the underside of the battery stack 10, the folded covering portion 32 may be formed only on the upper end side. For example, this would be the case when the battery cells are covered with a heat-shrinkable film.
(Positioning mechanism)

The power supply device 100 also has a positioning mechanism between the bus bar 40 that connects the electrode terminals 2 between adjacent battery cells 1 and the insulating spacer 16 that is interposed between the battery cells 1 on the underside of the bus bar 40. This makes it possible to position the bus bar 40 using the insulating spacer 16, making it easier to determine the welding positions for welding the bus bar 40 to the electrode terminal 2 for each battery cell 1.

In the past, power supplies with multiple stacked battery cells were designed to have a predetermined stack length. That is, as shown in FIG. 19, end plates 903 were placed on both sides of the battery stack 910, and the battery stack 910 was pressed by fastening with bind bars 904. However, since battery cells have dimensional differences due to manufacturing tolerances, etc., fastening to a predetermined length results in different pressing forces acting on the battery cells. Since the reaction force of the battery cells against the pressing force also differs, the load on the battery cells will vary from one power supply unit to another, which may cause differences in the performance and lifespan of the power supply units. Therefore, the inventors have studied how to realize a homogeneous, high-quality power supply unit by making the pressure for fastening the battery stack constant, thereby making the load on the battery cells constant and suppressing the occurrence of performance differences caused by variations in pressing force.

However, by applying a constant pressing force to the battery stack in this way, the stack length of the battery stack will not be constant due to individual differences in the battery cells. For example, as shown in Figures 5A to 5C, even if the same number of battery cells 1, 1, ..., which have individual differences in thickness, are stacked, the stack lengths BL1, BL2, and BL3 of the battery stack 10 will vary. In order to make the stack length of the resulting battery stack constant while maintaining a constant pressing force, multiple types of insulating spacers 16L with different thicknesses are prepared as insulating spacers to be interposed between the battery cells 1, and the stack length can be adjusted by selecting an insulating spacer 16L with an appropriate thickness as shown in Figure 6. Alternatively, the stack length may be adjusted by interposing an elastic body 72 as shown in Figure 7.

However, even if the length of the battery stack 10 is adjusted to a constant length using this method, the position of the electrode terminal 2 of each battery cell 1 differs, and the problem of inconsistent welding positions with the busbar 40' cannot be solved. Conventionally, because the battery stack was designed on the assumption that the length of the battery stack was fixed, the positions of the electrode terminals of each battery cell were generally uniform, and positioning for welding the electrode terminals to the busbar was relatively easy. In contrast, in a configuration in which the pressing force on the battery stack is constant, as shown in Figures 6 and 7, even if the stacking length of the battery stack 10 is adjusted to a constant length, the positions of the electrode terminals 2 of each battery cell 1 differ, and the position of the busbar 40' becomes inconsistent, creating a new problem in that welding of the busbar 40' to the electrode terminal 2 cannot be performed properly.

For example, if the electrode terminals have a structure that protrudes significantly like screw terminals, it is possible to use positioning using the electrode terminals. As an example, as shown in the cross-sectional view with an enlarged view of the main part of FIG. 8, a structure that allows each busbar 40X to be displaced in the stacking direction of the battery cells 1 is added to a busbar holder 34 that holds multiple busbars 40X that connect the protruding electrode terminals 2X together. In this example, the busbar holder 34 is made of resin, and a U-shaped hinge structure 37 is provided at the part that connects the busbar holding parts 36 that hold each busbar 40X together. In addition, each busbar 40X held by the busbar holding part 36 has a hole 58X into which the electrode terminal 2X can be inserted. In this way, by using the flexible hinge structure 37 as a guide for inserting the electrode terminal 2X into the hole 58X of the busbar 40X, the busbar 40X and the electrode terminal 2X can be positioned and fixed by screwing, welding, etc.

However, if the amount of protrusion of the electrode terminal is small, such an induction structure using the electrode terminal itself cannot be adopted. In recent years in particular, there has been an increasing demand for smaller power supply devices, and there is a trend toward requiring electrode terminals that protrude from the battery cell to also protrude less.

Therefore, in the power supply device 100 according to the first embodiment, as described above, the insulating spacer 16 is provided with a positioning mechanism for positioning the bus bar 40. Specifically, as shown in the enlarged perspective view of FIG. 3 and the exploded perspective view of FIG. 4, the positioning mechanism can be configured with an opening 58 opened in the bus bar 40 and a protrusion 28 formed in the insulating spacer 16 that is inserted into the opening 58. With this configuration, the protrusion 28 of the insulating spacer 16 can be inserted into the opening 58 of the bus bar 40, making it easier to position the welding position of the bus bar 40 for each battery cell 1.

As shown in FIG. 4, the insulating spacer 16 has a spacer bent piece 27 formed on the upper part of the spacer main surface 26 that faces the battery cell 1, protruding toward the sealing plate of the battery cell 1. The spacer bent piece 27 also has a pin-shaped protrusion 28 formed thereon.

On the other hand, the bus bar 40 has an opening 58 as described above. The opening 58 is formed to a size and shape that allows the protrusion 28 to be inserted. In the example of Figures 3 and 4, the protrusion 28 is cylindrical, and the opening 58 is a circular hole.

This configuration has the advantage that it can be applied even when the electrode terminal 2 protrudes only a small amount. For example, even if the electrode terminal protrudes 5 mm or less from the top surface of the outer can, this embodiment makes it possible to position the electrode terminal 2 and the bus bar 40 even for battery cells where mechanical positioning is difficult using only the electrode terminal, and welding can be performed appropriately to improve reliability.

The positioning mechanism is not limited to the combination of the circular hole-shaped opening 58 and the cylindrical protrusion 28. For example, as in the power supply device according to the modified example shown in Fig. 9, a combination of an elliptical cylindrical protrusion 28B and an elliptical opening 58B may be used. Also, as in the power supply device according to another modified example shown in Fig. 10, a combination of a plate-shaped protrusion 28C and a slit-shaped opening 58C may be used. Furthermore, the opening 58 does not need to be formed in an annular shape, and may be a combination of a notched opening 58D and a protrusion 28D as in the power supply device according to yet another modified example shown in Fig. 11.
[Embodiment 2]

In the above embodiment 1, an example has been described in which a positioning mechanism is provided directly between the bus bar 40 and the insulating spacer 16. However, the present invention is not limited to a configuration in which the positioning mechanism is provided on the bus bar side, and the positioning mechanism may be provided on another member. For example, a positioning mechanism for positioning the bus bar between the insulating spacer and a bus bar holder that holds the bus bar may be provided. Such an example is shown in Figs. 12 to 15 as a power supply device 200 according to embodiment 2 of the present invention. In these figures, Fig. 12 is a perspective view showing the power supply device 200 according to embodiment 2 of the present invention, Fig. 13 is an exploded perspective view of the power supply device 200 shown in Fig. 12, Fig. 14 is an enlarged perspective view showing a portion of the electrode terminal 2 of the power supply device 200 shown in Fig. 12, and Fig. 15 is an exploded perspective view of Fig. 14. The power supply device 200 shown in these figures comprises a battery stack 10 made up of multiple stacked battery cells 1 with insulating spacers 16 between them, end plates 20 covering the end faces of the battery stack 10, fastening members 15 that fasten the battery stack 10 together, bus bars 40 that connect the electrode terminals 2 of adjacent battery cells 1, and a bus bar holder 34 that holds the multiple bus bars 40. Note that components that are the same as those in the first embodiment described above are given the same reference numerals and detailed descriptions will be omitted where appropriate.
(Bus bar holder 34)

The busbar holder 34 is a member that holds multiple busbars 40. The busbars 40 are positioned by a positioning mechanism via the busbar holder 34. This makes it possible to position the busbars 40 using the insulating spacer 16 and the busbar holder 34, making it easier to determine the welding positions for welding the busbars 40 to the electrode terminals 2 for each battery cell 1.

In the example shown in Figures 14 and 15, the positioning mechanism is composed of an opening 38 in the bus bar holder 34 and a protrusion 28 formed in the insulating spacer 16 that is inserted into the opening 38. With this configuration, the protrusion 28 of the insulating spacer 16 can be inserted into the opening 38 of the bus bar holder 34, making it easier to position the welding position of the bus bar 40 for each battery cell 1.

The bus bar holder 34 is made of a resin with excellent insulating properties. For example, it is made of polybutylene terephthalate (PBT). The bus bar holder 34 may also be formed with a gas duct that introduces gas discharged from the gas exhaust valve of the battery cell and regulates the gas exhaust path that discharges the gas to the outside of the power supply device 200.

The busbar 40 is arranged in a fixed position by the busbar holder 34 shown in Figures 12 and 13, and guides the protruding portion 2A of the electrode terminal 2 to the opening window 62. The busbar holder 34 is molded from an insulating material such as plastic and arranges the busbar 40 in a fixed position. The busbar holder 34 is connected to the battery stack 10 to arrange the busbar 40 in a fixed position. The busbar holder 34 is connected to the insulating spacer 16 stacked between the battery cells 1 and arranged in a fixed position, or is connected to the battery cell 1 and connected to a fixed position of the battery stack 10. The busbar holder 34 shown in Figure 13 and other figures is configured by connecting multiple frame-shaped holder frames 35, which arrange each busbar 40 in a fixed position, for each busbar 40. The holder frame 35 is arranged on the upper surface of the battery stack 10 with the multiple busbars 40 arranged in their fixed positions, and the opening window 62 of each busbar 40 is arranged in the protruding portion 2A of the electrode terminal 2. In this state, laser light is irradiated from the upper opening of the holder frame 35, and the bus bar 40 is welded to the electrode terminal 2. After the bus bar 40 is welded to the electrode terminal 2, a cover plate may be provided to close the upper opening of the holder frame 35.

The power supply device 100 described above can be used as a vehicle power source that supplies power to a motor that runs an electric vehicle. Electric vehicles that can be equipped with the power supply device 100 include hybrid cars and plug-in hybrid cars that run on both an engine and a motor, and electric cars that run only on a motor, and the power supply device 100 is used as a power source for these vehicles. Note that an example will be described in which a large-capacity, high-output power supply device is constructed by connecting a large number of the above-mentioned power supply devices 100 in series or parallel to obtain power to drive an electric vehicle, and further adding a necessary control circuit.
(Power supply unit for hybrid vehicles)

FIG. 16 shows an example of a power supply device 100 mounted on a hybrid vehicle that runs on both an engine and a motor. The vehicle HV mounted with the power supply device 100 shown in this figure includes a vehicle body 91, an engine 96 and a motor 93 for running the vehicle body 91, wheels 97 driven by the engine 96 and the motor 93 for running, a power supply device 100 for supplying power to the motor 93, and a generator 94 for charging the battery of the power supply device 100. The power supply device 100 is connected to the motor 93 and the generator 94 via a DC/AC inverter 95. The vehicle HV runs on both the motor 93 and the engine 96 while charging and discharging the battery of the power supply device 100. The motor 93 is driven in an area where the engine efficiency is poor, such as during acceleration or low-speed running, to run the vehicle. The motor 93 is driven by power supplied from the power supply device 100. The generator 94 is driven by the engine 96 or by regenerative braking when braking the vehicle, and charges the battery of the power supply device 100. 16, the vehicle HV may be provided with a charging plug 98 for charging the power supply device 100. The power supply device 100 can be charged by connecting this charging plug 98 to an external power source.
(Power supply unit for electric vehicles)

FIG. 17 shows an example in which the power supply device 100 is mounted on an electric vehicle that runs only by a motor. The vehicle EV equipped with the power supply device 100 shown in this figure includes a vehicle body 91, a motor 93 for driving the vehicle body 91, wheels 97 driven by the motor 93, a power supply device 100 that supplies power to the motor 93, and a generator 94 that charges the battery of the power supply device 100. The power supply device 100 is connected to the motor 93 and the generator 94 via a DC/AC inverter 95. The motor 93 is driven by power supplied from the power supply device 100. The generator 94 is driven by energy generated when the vehicle EV is subjected to regenerative braking, and charges the battery of the power supply device 100. The vehicle EV also includes a charging plug 98, which can be connected to an external power source to charge the power supply device 100.
(Power supply device for power storage device)

Furthermore, the present invention does not limit the use of the power supply device to a power source for a motor that drives a vehicle. The power supply device according to the embodiment can also be used as a power source for a power storage device that charges a battery with electricity generated by solar power generation, wind power generation, etc. and stores the electricity. Figure 18 shows a power storage device that charges the battery of the power supply device 100 with a solar cell 82 and stores the electricity.

The power storage device shown in FIG. 18 charges the battery of the power supply device 100 with power generated by a solar cell 82 arranged on the roof or rooftop of a building 81 such as a house or factory. This power storage device charges the battery of the power supply device 100 with a charging circuit 83 using the solar cell 82 as a charging power source, and then supplies power to a load 86 via a DC/AC inverter 85. For this reason, this power storage device has a charging mode and a discharging mode. The power storage device shown in the figure connects the DC/AC inverter 85 and the charging circuit 83 to the power supply device 100 via a discharge switch 87 and a charge switch 84, respectively. The discharge switch 87 and the charge switch 84 are switched ON/OFF by the power storage device's power supply controller 88. In the charge mode, the power supply controller 88 switches the charge switch 84 to ON and the discharge switch 87 to OFF to allow charging from the charging circuit 83 to the power supply device 100. Furthermore, when charging is completed and the battery is fully charged, or when the battery is charged to a capacity equal to or greater than a predetermined value, the power supply controller 88 switches the charging switch 84 to OFF and the discharging switch 87 to ON to switch to discharging mode, allowing the power supply device 100 to discharge to the load 86. Also, if necessary, the charging switch 84 can be turned ON and the discharging switch 87 can be turned ON to simultaneously supply power to the load 86 and charge the power supply device 100.

Furthermore, although not shown, the power supply device can also be used as a power source for a power storage device that uses late-night power at night to charge and store electricity in a battery. A power supply device that is charged with late-night power is charged with late-night power, which is surplus electricity from power plants, and outputs electricity during the day when the power load is high, making it possible to limit daytime peak power to a low level. Furthermore, the power supply device can also be used as a power source that charges with both the output of solar cells and late-night power. This power supply device makes effective use of both the power generated by solar cells and late-night power, and can store electricity efficiently while taking into account the weather and power consumption.

The above-mentioned energy storage system can be ideally used for a variety of applications, including backup power supplies that can be mounted on computer server racks, backup power supplies for wireless base stations for mobile phones and the like, energy storage power supplies for home or factory use, power supplies for street lights, energy storage devices combined with solar cells, and backup power supplies for traffic lights and road traffic indicators.

The power supply device and the vehicle and power storage device according to the present invention can be suitably used as a large current power source for use in the power supply of motors that drive electric vehicles such as hybrid cars, fuel cell vehicles, electric cars, and electric motorcycles. Examples include power supply devices for plug-in hybrid electric cars, hybrid electric cars, electric cars, etc. that can switch between EV driving mode and HEV driving mode. They can also be used appropriately for applications such as backup power supplies that can be mounted on computer server racks, backup power supplies for wireless base stations for mobile phones, etc., power supplies for home and factory storage, power supplies for street lights, power storage devices combined with solar cells, and backup power supplies for traffic lights, etc.

100, 200, 900... Power supply device 1... Battery cell 1X... Terminal surface 1a... Outer can 1b... Sealing plate 1c... Gas exhaust valve 2... Electrode terminal 2A... Protrusion 2B... Joint surface 2X... Protruding electrode terminal 10... Battery stack 15... Fastening member; 15a... Fastening main surface; 15d... Bent piece 15f... Bolt 16, 16L... Insulating spacer 17... End surface spacer 20... End plate 26... Spacer main surface 27... Spacer bent piece 28, 28B, 28C, 28D... Protrusion
30...insulating sheet; 31...flat plate; 32...folded covering portion 34...busbar holder 35...holder frame 36...busbar holding portion 37...hinge structure 38...opening 40, 40', 40X...busbar 41...first connecting portion 42...first connecting bending region 43...first bending portion 44...first intermediate bending region 45...first intermediate portion 46...third intermediate bending region 47...third bending portion 49...connecting portion 51...second connecting portion 52...second connecting bending region 53...second bending portion 54...second intermediate bending region 55...second intermediate portion 56...fourth intermediate bending region 58, 58B, 58C, 58D...opening 58X...hole 61...thin region 62...opening window 72...elastic body 81...building 82...solar cell 83...charging circuit 84...charging switch 85...DC/AC inverter 86...load 87...discharge switch 88...power supply controller 91...vehicle body 93...motor 94...generator 95...DC/AC inverter 96...engine 97...wheels 98...charging plug 901...battery cell 902...electrode terminal 903...end plate 904...bind bar 910...battery stack 940...busbars BL1, BL2, BL3...stacking length of battery stack HV, EV...vehicle

Claims (8)

a battery stack formed by stacking a plurality of battery cells each having an electrode terminal on an upper surface of an outer casing;
a plurality of insulating spacers having insulating properties and interposed between the plurality of battery cells;
an end plate covering an end surface of the battery stack;
a fastening member for fastening the battery stack;
a plurality of bus bars connecting the electrode terminals of adjacent battery cells;
Equipped with
a positioning mechanism is provided between a bus bar that connects the electrode terminals of adjacent battery cells and the insulating spacer that is interposed between the battery cells on a lower surface of the bus bar ,
The positioning mechanism includes:
an annular opening formed in the bus bar;
a protrusion formed on the insulating spacer and inserted into the annular opening;
A power supply device comprising : 2. The power supply device of claim 1, further comprising:
a bus bar holder for holding the plurality of bus bars;
The bus bar is positioned by the positioning mechanism via the bus bar holder. 3. The power supply device according to claim 1 or 2 , further comprising:
The power supply device further comprises an elastic body for adjusting a pressure thickness before the end plates are pressed against each other. The power supply device according to any one of claims 1 to 3,
The power supply device wherein the annular opening is opened in the shape of a circular hole. The power supply device according to any one of claims 1 to 4 ,
The electrode terminals may protrude from the top surface of the outer can by 5 mm or less. a battery stack formed by stacking a plurality of battery cells each having an electrode terminal on an upper surface of an outer casing;
a plurality of insulating spacers having insulating properties and interposed between the plurality of battery cells;
an end plate covering an end surface of the battery stack;
a fastening member for fastening the battery stack;
a plurality of bus bars connecting the electrode terminals of adjacent battery cells;
Equipped with
a positioning mechanism is provided between a bus bar that connects the electrode terminals of adjacent battery cells and the insulating spacer that is interposed between the battery cells on a lower surface of the bus bar,
The positioning mechanism includes:
an opening formed in the bus bar;
a protrusion formed on the insulating spacer and inserted into the opening;
It is composed of
The electrode terminals may protrude from the top surface of the outer can by 5 mm or less. A vehicle equipped with the power supply device according to any one of claims 1 to 6,
A vehicle comprising the power supply device, a motor for driving supplied with power from the power supply device, a vehicle body mounting the power supply device and the motor, and wheels driven by the motor to drive the vehicle body. A power storage device comprising the power supply device according to any one of claims 1 to 6,
A power storage device comprising the power supply device and a power supply controller that controls charging and discharging to the power supply device, the power supply controller enabling charging of the battery cells using external power and controlling the charging of the battery cells.

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