Patent Application
20170358785
The present invention relates to a power supply device in which a plurality of secondary batteries capable of charging and discharging are stacked, and to a vehicle including the power supply device.
In a power supply device for a vehicle, multiple secondary batteries capable of charging and discharging are connected in series into a battery block, and the output voltage of the battery block is set high to increase power to be supplied to a motor for running the vehicle. This power supply device is discharged by supplying power to the motor in a running state of the vehicle, and is charged by a power generator in regenerative braking of the vehicle. The discharging current of the batteries specifies the driving torque of the motor, and the charging current of the batteries specifies the braking force for regenerative braking. Therefore, it is necessary to increase the discharging current of the batteries in order to increase the driving torque of the motor for accelerating the vehicle, and it is necessary to charge the batteries with a large current in order to increase regenerative braking of the vehicle. Accordingly, the batteries in the power supply device for the vehicle are discharged or charged with a large current. To improve safety in discharging and charging the batteries with a large current, there has been developed a battery including a mechanism that interrupts the current when the internal pressure of the battery abnormally increases, that is, a current interrupt device.
As a battery including such a current interrupt device, for example, there has been proposed a secondary battery including a device that interrupts the current by fusing a contained fuse part when the internal pressure of the battery exceeds a set pressure (see PTL 1). As illustrated in
PTL 1: Japanese Published Unexamined Patent Application No. 2012-195278
The current can be reliably interrupted by fusing of the fuse part contained in the secondary battery by completely fusing and cutting off the fuse part. In an actual secondary battery, however, it is difficult to completely fuse the fuse part in a limited narrow space inside the battery. It is conceivable that a spark will occur at the time of fusing and that a spark will be caused by reconduction resulting from the contact between fused portions.
Particularly when the fuse part is fused in the vehicular power supply device, the current is interrupted and motor driving cannot be performed, but, for example, a hybrid car can run by using the engine. However, it is conceivable that, if engine driving is performed in this state, the fused portions may come into contact with each other inside the secondary battery and a spark may be caused by reconduction. In particular, in the secondary battery mounted in the vehicle, vibration due to driving of the vehicle cannot be completely removed. It is conceivable that the fused portions may be brought into contact with each other by external vibration and a spark may be easily caused by reconduction. From these, the present inventors considered that, in the secondary battery including the current interrupt device for interrupting the current by fusing the fuse part, the occurrence of the spark at the time of fusing and reconduction could not be completely avoided and that it was necessary to take measures to prevent scattering of the spark to the outside of the secondary battery.
The present invention has been made in view of these problems of the related art. An object of the invention is to provide a power supply device that can effectively prevent a spark from scattering to the outside of a secondary battery even if the spark occurs at fused portions and damages an outer can when a fuse part contained in the second battery is fused and reconducted, and a vehicle including the power supply device.
To achieve the above object, a power supply device according to the present invention includes a battery stack in which a plurality of secondary batteries are stacked, and a binding member that binds the battery stack. Each of the secondary batteries includes an electrode body having a positive electrode and a negative electrode, an outer can having an opening and shaped like a bottomed cylinder to contain the electrode body, a sealing plate that closes the opening of the outer can, a pair of electrode terminals disposed on the sealing plate, and a current interrupt device that operates when an internal pressure of the secondary battery exceeds a set pressure. The pair of electrode terminals include a first electrode terminal insulated from the sealing plate and a second electrode terminal electrically connected to the sealing plate, and are electrically connected to the electrode body through a collector member inside the secondary battery. The current interrupt device includes a short-circuit part that short-circuits the first electrode terminal and the sealing plate when the internal pressure of the secondary battery exceeds the set pressure, and a fuse part provided in the collector member. The fuse part is disposed close to an upper end corner portion serving as a boundary portion between an upper surface and a side surface of the secondary battery, and is fused by an overcurrent in a short-circuit state of the short-circuit part. The binding member includes a protective cover portion located on each side of the battery stack to cover the upper end corner portion of the secondary battery. The protective cover portion includes an upper-surface covering part that covers an upper surface of the upper end corner portion and a side-surface covering part that covers a side surface of the upper end corner portion.
In this description, the up-down direction of the secondary battery is specified in the drawings. The side surface of the second battery refers to a narrow surface on each side of a battery stack in which a plurality of secondary batteries are stacked with wide principal surfaces opposed to each other.
The present invention is effective particularly when the fuse part is located in a region at a direct distance of 2 cm or less from the upper end corner portion. Further, the present invention is more effective when the fuse part is located in a region at a direct distance of 1 cm or less from the upper end corner portion. Preferably, the collector member has a platelike portion, and the fuse part is constituted by a portion having a small cross-sectional area obtained by forming an opening in the platelike portion. The present invention is more effective when the fuse part is located in a region of the collector member between the sealing plate and the electrode body. Further, the present invention is more effective when the platelike portion of the collector member having the fuse part is located parallel to the sealing plate.
According to the power supply device having the above-described structure, the fuse part in the current, interrupt device is located close to the upper end corner portion of the secondary battery, and the binding member that binds the battery stack has the protective cover portion that covers the upper end corner portion of the secondary battery. Hence, even if a spark occurs at fused portions and damages the outer can during fusing and reconduction of the contained fuse part, the spark can be effectively prevented from scattering to the outside of the second battery. In particular, since the protective cover portion includes the upper-surface covering part that covers the upper surface of the upper end corner portion and the side-surface covering part that covers the side surface, the protective cover portion can reliably cover the upper end corner portion of the secondary battery and can effectively prevent scattering of the spark from the upper end corner portion.
In the power supply device of the present invention, the binding member can be a bind bar formed by bending a metal plate having a predetermined thickness. According to the above structure, the binding member can be easily produced at low cost by bending the metal plate.
In the power supply device of the present invention, an insulating member can be provided on an inner surface of the bind bar. According to the above structure, while the binding member is the metal plate, a portion thereof opposed to the battery stack can be insulated and safely used.
In the power supply device of the present invention, the bind bar can include an upper bind bar that covers an upper portion of a side surface of the battery stack and a lower bind bar that covers a lower portion of the side surface of the battery stack, and the upper bind bar can also function as the protective cover portion. According to the structure, since the battery stack is connected by four bind bars, four corners of the battery stack can be bound in an ideal state by the bind bars.
In the power supply device of the present invention, the bind bar can have a body portion opposed to a side surface of the battery stack, and the body portion can cover the entire side surface of the battery stack. According to the above structure, the mechanical strength can be increased by widening the bind bar opposed to the side surface of the battery stack. Moreover, since the side surface of the battery stack is entirely covered, the spark can be reliably prevented from scattering toward the side surface of the battery stack.
In the power supply device of the present invention, the bind bar can have a body portion opposed to a side surface of the battery stack, and the body portion can have an open window. According to the above structure, the weight of the bind bar opposed to the side surface of the battery stack can be reduced, and heat can be effectively dissipated by exposing the side surface of the secondary battery from the open window.
In the power supply device of the present invention, the bind bar can have a horizontal portion that covers at least a part of a bottom surface of the battery stack. According to the above structure, since at least a part of the bottom surface of the battery stack is covered with the horizontal portion, a plurality of stacked secondary batteries can be bound while positioning the bottom surfaces of the secondary batteries, and the vibration-resistant strength can be further increased by further suppressing the relative movement in the up-down direction.
A vehicle according to the present invention includes any of the above-described power supply devices.
According to the vehicle having the above-described structure, while the power supply device having a plurality of secondary batteries is mounted in the vehicle, the binding member that, binds the battery stack is provided with the protective cover portion that covers the upper end corner portion of each of the secondary batteries. Hence, even if a spark occurs at fused portions and damages the outer can at the time of fusing and reconduction of the contained fuse part, the spark can be effectively prevented from scattering to the outside of the second battery. In particular, since the protective cover portion of the binding member includes the upper-surface covering part that covers the upper surface of the upper-end corner portion and the side-surface covering part that covers the side surface, the protective cover portion can reliably cover the upper end corner portion of the secondary battery and can effectively prevent the spark from scattering from the upper end corner portion.
As illustrated in an exploded perspective view of
The assembled batteries 10 are fixed at determined positions inside the outer case 70. In the example of
As illustrated in
The lower case 71 also functions as a cooling plate that cools the battery stack 5. That is, heat generated by the secondary batteries 1 is thermally conducted to the lower case 71 to promote heat dissipation by thermally bonding the bottom surfaces of the secondary batteries 1 to the lower case 71. A cooling pipe for circulating a refrigerant may be disposed on a lower surface or an inner side of the lower case 71. The separators 2 may have grooves through which a cooling gas is passed to cool the secondary batteries 1.
In each assembled battery 10, a plurality of secondary batteries 1 are stacked with insulating separators 2 interposed therebetween to form a battery stack 5, a pair of end plates 3 are disposed on both end faces of the battery stack 5, and the pair of end plates 3 are connected by binding members 4. In the assembled battery 10 illustrated in these figures, the separators 2 for insulating the adjacent secondary batteries 1 are interposed between stacking surfaces of the secondary batteries 1, and the secondary batteries 1 and the separators 2 are alternately stacked to constitute the battery stack 5.
In the assembled battery, the separators do not always need to be interposed between the secondary batteries. For example, the separators can be omitted by insulating the adjacent second batteries by means of a method of forming outer cans of the secondary batteries of an insulating material such as resin, or a method of covering outer peripheries of the outer cans of the secondary batteries with heat-shrinkage tubes, insulating sheets, or an insulating paint. Particularly in a structure that adopts a method of cooling the battery stack through a cooling pipe cooled by, for example, a refrigerant, without using an air cooling method of cooling the secondary batteries by forcibly blowing cooling air between the secondary batteries, it is not always necessary to interpose the separators between the secondary batteries.
As illustrated in
As illustrated in
The sealing plate 12 has a gas discharge valve 14 between the pair of electrode terminals 13. The gas discharge valve 14 opens to discharge inner gas when the internal pressure of the outer can 11 rises to a pressure higher than or equal to a predetermined pressure. By opening the gas discharge valve 14, the rise of the internal pressure of the outer can 11 can be suppressed. The gas discharge valve 14 is preferably disposed at almost, the longitudinal center of the sealing plate 12. Thus, even if the adjacent secondary batteries 1 are stacked while being alternately reversed in the lateral direction, the gas discharge valve 14 can be always aligned with the center of the sealing plate 12. Further, the sealing plate 12 has a liquid injection portion 19 adjacent to the gas discharge valve and allowing injection of an electrolyte therethrough. The secondary battery 1 is produced by inserting the electrode body 15 in the outer can 11, hermetically sealing the opening of the outer can 11 with the sealing plate 12, and then injecting an electrolyte (not illustrated) from the liquid injection portion 19.
The pair of electrode terminals 13 includes a first electrode terminal 13A insulated from the sealing plate 12 and a second electrode terminal 13B electrically connected to the sealing plate 12. The pair of electrode terminals 13 are fixed to determined positions on the sealing plate 12 with gaskets 17 interposed therebetween. The first electrode terminal 13A is connected to the sealing plate 12 in an insulated state with the gasket 17 interposed therebetween. The second electrode terminal 13B is connected to the sealing plate 12 with the gasket 17 interposed therebetween, and is electrically connected to an upper surface side of the sealing plate 12 with a metallic fixed member 18, which is fixed to the second electrode terminal 13B, interposed therebetween. Inside the secondary battery 1, the positive and negative electrode terminals 13 fixed to the sealing plate 12 are electrically connected to the electrode body 15 with collector members 16 interposed therebetween. In the secondary battery 1, the second electrode terminal 13B connected to the sealing plate 12 and the outer can 11 serves as a positive terminal, and the first electrode terminal 13A serves as a negative terminal.
To avoid a thermal runaway, for example, due to overcharging, each of the secondary batteries 1 includes a current interrupt device 7 that breaks electric connection between the electrode body 15 and the second electrode terminal 13B in response to the rise of the internal pressure of the outer can 11. The illustrated current interrupt device 7 includes a short-circuit part 20 that short-circuits the first electrode terminal 13A and the sealing plate 12 when the internal pressure of the secondary battery 1 exceeds the set pressure, and a fuse part 21 provided in the collector member 16 connected to the second electrode terminal 13B. In the current interrupt device 7, in a state in which the internal pressure of the battery exceeds the set pressure and the short-circuit part 20 makes a short circuit, the fuse part 21 is fused by an overcurrent flowing through the fuse part 21. As a result, the electrical connection between the electrode body 15 and the second electrode terminal 13B is broken and the current is interrupted.
When the internal pressure of the secondary battery 1 exceeds the set pressure, for example, owing to overcharging, the short-circuit part 20 serves to induce a short circuit so that a large current flows through the fuse part 21. The short-circuit part 20 illustrated in
As illustrated in
While one inverting plate 22 is provided in the short-circuit part 20 of this example, a plurality of inverting plates may be stacked. In a short-circuit part including a plurality of stacked inverting plates, when the inverting plates are made different in thickness and set inverting pressure, it is possible to more smoothly respond to the rise of the internal pressure of the battery and to continue the fuse function of the fuse part while maintaining a short circuit of one of the inverting plates even when the other inverting plate is fused by heat.
The connection plate 23 is disposed on the upper surface of the sealing plate 12 with an insulating portion 24 interposed therebetween, and is connected to the sealing plate 12 in an insulated state. The connection plate 23 is electrically connected to the first electrode terminal 13A. Specifically, the first electrode terminal 13A is passed through a hole opening in a part of the connection plate 23, and the connection plate 23 and the first electrode terminal 13A are electrically connected through the fixed member 18 fixed to the first electrode terminal 13A on the upper side of the connection plate 23.
The fuse part 21 is to be fused and cut off by heat generated by an overcurrent flowing through the battery in a short-circuit state of the short-circuit part 20, and is disposed in a conduction path of the current at the time of a short circuit. The fuse part 21 illustrated in
The fuse part 21 illustrated in
In the above-described fuse part 21, the connecting portion 21B is fused and cut off in the region where the fuse hole 21A or the cutout are provided. This electrically separates the platelike portion 16A of the collector member 16 and interrupts the current. As illustrated in
The fuse part 21 is preferably obtained by forming an opening in the platelike portion 16A of the collector member 16. Further, the thickness of the sealing plate 12 is preferably more than or equal to double the thickness of the platelike portion 16A of the collector member 16.
In the current interrupt device 7 illustrated in
In the above-described current interrupt device 7, when the internal pressure of the secondary battery 1 becomes higher than or equal to the set pressure, as illustrated in
As illustrated in
In the assembled battery 10 in which the secondary batteries 1 are connected in series, as illustrated in the perspective views of
The secondary batteries 1 are constituted by the metallic outer cans 11. The secondary batteries 1 hold the insulating separators 2 therebetween to prevent a short, circuit between the outer cans 11 of the adjacent secondary batteries 1. The separators 2 are spacers that allow the adjacent secondary batteries 1 to be stacked while being electrically and thermally insulated from each other. The separators 2 are made of an insulating material such as resin, and are disposed between the adjacent secondary batteries 1 to insulate the adjacent secondary batteries 1.
A pair of end plates 3 are disposed on both end surfaces of the battery stack 5 in which the secondary batteries 1 and the separators 2 are alternately stacked, and the pair of end plates 3 bind the battery stack 5. The end plates 3 are made of a material that exhibits a sufficient strength, for example, metal. The end plates 3 have fixing structures to be fixed to the lower case 71 illustrated in
As illustrated in
The binding members 4 serving as the bind bars 40 extend in the stacking direction of the battery stack 5, and are each fixed at. both ends to the pair of end plates 3. Each of the bind bars 40 has a body portion 41 disposed along the side surface of the battery stack 5, and connecting pieces 42 disposed at both ends of the body portion 41 and fixed to the end plates 3. Bind bars 40A illustrated in
Each of the upper bind bars 40X has an L-shaped cross section defined by connecting pieces 42 at both ends of a body portion 41 of a predetermined width and a horizontal portion 43 at an upper end of the body portion 41 to cover the upper surface of the battery stack 5. In each of the upper bind bars 40X illustrated in
The connecting pieces 42 at both ends of the body portion 41 are bent perpendicularly to the body portion 41 to be in surface contact with outer side surfaces of the end plates 3. Although not illustrated, both ends of each bind bar 40 are fixed to the end plates 3 by connectors such as setscrews, are fixed to the end plates 3 by a retaining structure, or are fixed to the end plates 3 by bonding or welding. In each bind bar 40 illustrated in
The binding members 4 further include protective cover portions 8 that cover upper end corner portions 1T at boundaries of the upper surfaces 1A and the side surfaces 1B of the secondary batteries 1. The protective cover portions 8 are disposed to cover the upper end corner portions 1T of the secondary batteries 1 close to the fuse parts 21 contained in the outer cans 11. In each illustrated secondary battery 1, since the fuse part 21 is provided in the collector member 16 that connects the second electrode terminal 13B at the end of the sealing plate 12 and the electrode body 15, the protective cover portion 8 is disposed to cover an edge where the second electrode terminal 13B is disposed in a connecting portion between the sealing plate 12 and the outer can 11. In the binding member 4 of this example, the upper bind bar 40X also functions as the protective cover portion 8.
The protective cover portion 8 illustrated in
When a spark occurs inside the secondary battery 1, a portion near the joint portion between the opening of the outer can 11 and the sealing plate 12 is most subject to breakage. Therefore, the shape and size of the protective cover portion 8 are such as to cover a region provided near the upper end corner portion 1T of the secondary battery 1 and including at least a welded portion 25 between the opening of the outer can 11 and the edge of the sealing plate 12. In the illustrated secondary battery 1, the boundary portion is welded at the opening of the outer can 11 in a state in which the outer peripheral edge of the sealing plate 12 is fitted inside the edge of the opening of the outer can 11. Therefore, in the secondary battery 1, the welded portion 25 between the outer can 11 and the sealing plate 12 is provided on the upper surface of the secondary battery 1. In the protective cover portion 8 illustrated in
In the secondary battery, however, the welded portion does not always need to be provided on the upper surface. Although not illustrated, the boundary portion can also be welded in a state in which the outer peripheral edge of the sealing plate is in contact with the opening edge of the opening of the outer can. In this secondary battery, a welded portion between the outer can and the sealing plate is provided on an outer peripheral surface (side surface and principal surface) of the secondary battery along the outer peripheral edge of the sealing plate. In the secondary battery having this structure, the side-surface covering part covering the side surface of the upper end corner portion covers the welded portion outside the opening edge of the outer can.
In the assembled battery 10 in which the plurality of secondary batteries 1 are connected in series, as described above, the adjacent secondary batteries 1 are stacked in such a posture to be alternately reversed in the lateral direction to connect the adjacent positive and negative electrode terminals 13 by the bus bars 6 in the shortest distance. For this reason, the positions of the fuse parts 21 contained in the secondary batteries 1 alternately differ between the adjacent secondary batteries 1. Therefore, in this assembled battery 10, as illustrated in
The assembled battery 10 illustrated in
In the above-described embodiment, the binding members 4 are constituted by four bind bars 40A, the upper bind bars 40X bind the upper portions of the side surfaces of the battery stack 5, and the lower bind bars 40Y bind the lower portions of the battery stack 5. Although not illustrated, according to this structure, in an air-cooled power supply device that cools secondary batteries by forcibly blowing cooling air between the secondary batteries, the cooling air can be passed and blown through ventilations defined by gaps serving between the upper bind bars and the lower bind bars. However, in the present invention, the binding members 4 on each side of the battery stack 5 can also be constituted by one bind bar 40B.
In an assembled battery 10 illustrated in
Alternatively, the binding members 4 can be configured to cover at least a part of the bottom surface of the battery stack 5. For example, the binding members 4 can cover corner portions on the bottom side of the battery stack 5 by providing horizontal portions 43 at lower ends of the bind bars 40.
Bind bars 40C illustrated in
Bind bars 40D illustrated in
Further, in the binding members 4, the body portions 41 covering the side surfaces of the battery stack 5 can have open windows. In bind bars 40E and 40F illustrated in
In the bind bars 40E of
In the bind bars 40F of
Since these bind bars 40E and 40F have the open windows 44, the weight and cost of the bind bars 40E and 40F are reduced. Further, heat can be efficiently dissipated from the secondary batteries by exposing the side surfaces of the battery stack from the open windows 44. Although not illustrated, in particular, in an air-cooled power supply device that cools secondary batteries by forcibly blowing cooling air between the secondary batteries, the cooling air can be passed and blown through the open windows provided as ventilations in the bind bars.
The above-described power supply devices can be used as a vehicle-mounted power supply. As vehicles in which the power supply device is mounted, electrically driven vehicles, such as a hybrid car and a plug-in hybrid car that run by using both an engine and a motor and an electric car that runs by using only a motor can be used. The power supply device is used as a power supply for these vehicles.
The embodiments and examples of the present invention have been described above with reference to the drawings. However, the above-described embodiments and examples are just illustrative examples for embodying the technical idea of the present invention, and the present, invention is not limited to the above embodiments and examples. This description does not specify the members in the scope of the claims to the members in the embodiments. In the above description, the same names and symbols denote the same or equivalent members, and detailed descriptions thereof are appropriately omitted. Further, in the elements that constitute the present invention, a plurality of elements may be constituted by the same member so that one member functions as a plurality of elements. Conversely, the function of one member may be shared and realized by a plurality of members.
The power supply device and the vehicle including the power supply device according to the present invention can be suitably used as a power supply device for, for example, a plug-in hybrid electric car and a hybrid electric car capable of switching an EV running mode and an HEV running mode and an electric car. The power supply device can be appropriately used for applications as a backup power supply device mountable in a computer server rack, a backup power supply device for a wireless base station of, for example, a mobile phone, a power storage device used in combination with a solar battery, such as a domestic or factory storage power supply or a power supply of a street light, and a backup power supply of a traffic light.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2015-039361 | Feb 2015 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2016/000976 | 2/24/2016 | WO | 00 |
