JP4127060B2 - Lithium ion batteries for vehicles - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle lithium ion assembled battery, and more particularly to a vehicle lithium ion assembled battery in which a plurality of box-type lithium ion batteries are combined to form an assembled battery.
[0002]
[Prior art]
Conventionally, nickel-hydrogen batteries have been used as batteries for supplying electric power to electric devices and the like mounted on vehicles. For example, Patent Document 1 discloses a nickel-hydrogen assembled battery configured by arranging a plurality of prismatic unit batteries in parallel. Since the open circuit voltage of the nickel-hydrogen battery is about 1.2 V, it is inconvenient because the number of series connection stages is increased in order to obtain a high voltage necessary as a power source for vehicles. Therefore, a lithium ion battery having an open circuit voltage as high as about 3.6 V has been attracting attention.
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-196103
[Problems to be solved by the invention]
Lithium ion batteries have an open circuit voltage approximately three times higher than that of nickel-hydrogen batteries, but still require multiple stages of connection to be used as a power source for vehicles. For example, when used as a starter power supply that requires an output voltage of about 14.4 V, it is convenient in handling that a lithium ion battery having an open-end voltage of 3.6 V is connected in series in four stages to form one assembled battery. .
[0005]
Regarding the structure of the assembled battery, in Patent Document 1, in the assembled battery in which the rectangular parallelepiped unit cells are arranged in parallel so that the side surfaces of the maximum area are overlapped and the cooling medium passage is formed between the unit cells, An example is disclosed in which a cooling medium passage is formed by interposing a spacer made of a metal material between opposing surfaces between unit cells.
[0006]
However, since a lithium ion battery dislikes moisture due to its electromotive force mechanism, a metal casing is used for the battery. In this respect, since there is no such restriction, it is greatly different from a nickel-hydrogen battery in which a resin casing is generally used. That is, from the battery configuration of the lithium ion battery, the potential of the metal housing is an intermediate potential between the positive electrode potential and the negative electrode potential of the lithium ion battery. When the metal casings of the lithium ion batteries come into direct contact with each other, the potentials are equal to each other, so that a sufficient open-ended voltage as an assembled battery cannot be obtained.
[0007]
Although it is conceivable to perform an insulating film laminating process on the front side of each housing, the extra cost is required for the insulating process, and when the insulating process is defective, it does not function sufficiently as an assembled battery. In addition, it is conceivable that an insulating plate is interposed between the metal casings. However, in general, an insulator has a poor thermal conductivity, and heat dissipation characteristics as an assembled battery cannot be ensured.
[0008]
In addition, the lithium ion battery has a problem of so-called cycle characteristic deterioration in which the number of charge / discharge cycles is gradually decreased by repeating charge / discharge. When charging / discharging is repeated, the casing swells. Therefore, in order to improve cycle characteristics, pressure is applied to the casing to suppress deformation. Considering the use of an assembled battery, it is convenient to apply pressure after collecting a plurality of lithium ion batteries rather than applying pressure to each lithium ion battery. Also in this case, as described above, if a plurality of housings are directly contacted to apply pressure, or pressure is applied to the plurality of housings through a metal plate having good heat dissipation, an open end sufficient for an assembled battery is obtained. If a voltage cannot be obtained and pressure is applied to a plurality of housings via an insulating plate, sufficient heat dissipation characteristics cannot be obtained.
[0009]
An object of the present invention is to provide a lithium-ion assembled battery for a vehicle that can solve the problems of the prior art and improve the cycle characteristics of the lithium-ion battery. Another object is to provide a lithium ion battery for a vehicle that can improve heat dissipation characteristics.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, a lithium ion assembled battery for a vehicle according to the present invention is a lithium ion assembled battery for a vehicle that combines a plurality of box-type lithium ion batteries into an assembled battery and supplies power to the vehicle equipment. A flat box-type housing made of metal, arranged in contact with both sides of each lithium-ion battery, and a plurality of lithium-ion batteries arranged side-by-side with a space between them, and the surface is insulated. A plurality of heat-dissipating metal plates, a pair of end plates provided at both outer ends of a laminate in which a plurality of lithium-ion batteries and a plurality of heat-dissipating metal plates are alternately stacked, and restrained by both outer ends of the pair of end plates A restraining means for applying a force and applying a clamping pressure to both outer ends of each laminate, and the heat dissipation metal plate has a lateral width of the side surface of the lithium ion battery defined by a height and a lateral width in the middle of the plate thickness. Along the direction And having a plurality of heat dissipation through holes in the direction.
[0011]
With the above configuration, a laminated body is formed by alternately laminating a plurality of lithium ion batteries having a flat metal box housing made of metal and a plurality of heat dissipating metal plates whose surfaces are subjected to insulation treatment. A pair of end plates are provided at both outer ends. Then, a binding force is applied to both outer ends of the pair of end plates to apply a clamping pressure to both outer ends of the laminate. Therefore, since the heat-dissipating metal plate whose surface is subjected to insulation treatment is disposed between the flat box-type housings made of metal, the metal housings are electrically insulated, which is sufficient as an assembled battery. The open circuit voltage can be secured and the heat dissipation characteristics can be improved. Furthermore, since a clamping pressure is applied to both outer ends of the laminate in this state, the cycle characteristics of the lithium ion battery can be improved.
[0012]
Moreover, it is preferable that a heat radiating metal plate is the aluminum plate by which the surface was anodized. With the above configuration, a lithium ion battery for a vehicle that is lightweight and has good heat dissipation characteristics can be obtained. Further, the heat radiating metal plate is preferably a metal plate having an insulating resin film formed on the surface. Further, the heat radiating metal plate is preferably a metal plate having a ceramic film formed on the surface thereof.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view of a lithium ion assembled battery 10 and FIG. 2 is a side view thereof. The lithium ion battery pack 10 is composed of four lithium ion batteries 12a, 12b, 12c, and 12d and five metal heat dissipation plates 14a, 14b, 14c, 14d, and 14e that are insulated on the surface. The laminated body 16 is included. Around the laminated body 16, a pair of end plates 18a, 18b and fastening belts 20a, 20b attached to the end plates 18a, 18b (the fastening belt 20b is disposed on the back side of the laminated body 16 and appears in the figure. The end plates 18a and 18b and the fastening belts 20a and 20b are fastened to each other as will be described later.
[0014]
FIG. 3 is a diagram showing the configuration of the lithium ion battery 12. The lithium ion battery 12 includes a metal flat box-shaped housing 30 having an upper opening, a lid 32 that fits into the upper opening of the housing 30, and a battery stack roll body 34 that is housed inside the housing 30. And an electrolytic solution to be immersed in the battery laminated roll body 34.
[0015]
For example, the casing 30 is formed by drawing a metal plate having a thickness of about 1 mm into a flat box having a height of about 102 mm, a wider width of about 120 mm, and a narrower width of about 25 mm. it can. If necessary for handling, the outer surface of the housing may be subjected to a surface treatment such as insulation coating. The lid 32 is attached with a positive electrode extraction portion 40 and a negative electrode extraction portion 42 which are insulated from each other. A metal plate made of the same material as that of the housing 30 can be used for the lid 32. In this case, an insulating layer such as a resin or ceramic is provided between the lid 32 and the positive electrode extraction portion 40 and the negative electrode extraction portion 42. Provided.
[0016]
As shown in the developed view of FIG. 4, the battery stack roll body 34 is overlapped with a separator 48 sandwiched between two electrode bodies 44 and 46 coated with an active material, and this is wound into a roll shape. Is. One electrode body 44 of the two electrode bodies has an aluminum foil as a base material, an active material is coated on the surface thereof, and a positive electrode portion 50 for taking out electric charges is connected to an aluminum portion by welding or the like. In the other electrode body 46, copper foil is a base material, an active material is applied thereon, and a negative electrode portion 52 for taking out electric charges is connected to a copper portion by welding or the like. The battery stack roll body 34 is formed by stacking the electrode body 44, the separator 48, and the electrode body 46 in this order and winding them in a roll shape so that the positive electrode portion 50 and the negative electrode portion 52 protrude from the upper opening of the housing 30. Then, it is housed inside the housing 30, and then an electrolytic solution is injected and penetrates between the electrode body 44, the separator 48, and the electrode body 46. The positive electrode portion 50 and the negative electrode portion 52 of the battery stack roll body 34 are connected to the positive electrode extraction portion 40 and the negative electrode extraction portion 42 of the lid 32, respectively.
[0017]
The lithium ion batteries 12a, 12b, 12c, and 12d are arranged in alignment with the side surfaces facing each other at intervals. Here, the side surface means a side surface having a larger area among the side surfaces of the flat box-type housing, and in the above example, the side surface has a height of about 102 mm and a lateral width of about 120 mm. As for the alignment arrangement, the arrangement of the positive electrode extraction portion 40 and the negative electrode extraction portion 42 is reversed every other so that the four lithium ion batteries 12a, 12b, 12c, 12d can be easily connected in series. can do. In other words, the positive electrode extraction portion 40b of the lithium ion battery 12b is adjacent to the negative electrode extraction portion 42a of the lithium ion battery 12a, and the positive electrode extraction portion 40c of the lithium ion battery 12c is adjacent to the negative electrode extraction portion 42b of the lithium ion battery 12b. The positive electrode extraction part 40d of the lithium ion battery 12d is disposed adjacent to the negative electrode extraction part 42c of the lithium ion battery 12c.
[0018]
If adjacent 42a and 40b, 42b and 40c, 42c and 40d are connected here, between the positive electrode extraction part 40a and the negative electrode extraction part 42d, open-circuit voltage 3.6V × 4 = 14.4V can be taken out.
[0019]
5 and 6 are perspective views showing examples of a metal heat radiating plate whose surface is subjected to insulation treatment. The metal heat radiating plate 60 shown in FIG. 5 is obtained by applying alumite treatment to a surface of an aluminum plate having a flat surface of about 2-5 mm as a base material. The size of the surface contacting the side surface of the lithium ion battery is preferably set slightly smaller than the side surface of the lithium ion battery. For example, in the above example, the height is 90 mm, the width is 85 mm, and the like. The metal heat radiating plate 62 shown in FIG. 6 has a plurality of through holes 64 for heat radiating in the width direction, for example, in the middle of the aluminum plate thickness. Also in this case, the alumite treatment is applied to the surface.
[0020]
Instead of alumite treatment, an insulating resin film may be formed on the surface of the base material. For example, a thermosetting synthetic resin such as polyimide, phenol resin, or polyamideimide can be applied to the surface of the base material. Further, a ceramic film may be formed on the surface of the base material. For example, the surface of the base material can be coated by spraying alumina (aluminum oxide) or zirconia by a plasma melting method. A metal other than aluminum may be used for the base material.
[0021]
The metal heat radiating plate whose surface is subjected to insulation treatment is disposed in contact with both side surfaces of each lithium ion battery. In the example of FIG. 2, since there are four lithium ion batteries, a total of three lithium ion batteries are provided in the gaps between the lithium ion batteries arranged at intervals, on the outer side surfaces of the lithium ion batteries 12a and 12d at both outer ends. Correspondingly, a total of two metal heatsinks are used, for a total of two.
[0022]
Returning to FIG. 1 and FIG. 2 again, the periphery of the end plates 18a and 18b will be described. The end plates 18 a and 18 b are formed by pressing a metal plate or the like, and are disposed in contact with the metal heat radiation plates 14 a and 14 e at both outer ends of the laminate 16. Since the end plates 18a and 18b are plates for performing the function of fastening the laminate 16, it is preferable to provide appropriate corrugated shapes and ribs so that the fastening pressure can be sufficiently transmitted to the metal heat radiating plates 14a and 14e. . The end plates 18a and 18b may be provided with mounting holes 22 for attaching the lithium ion battery pack to the vehicle.
[0023]
As described above, the fastening belt 20a extending toward the end plate 18b along the periphery of the stacked body 16 is attached to the end plate 18a. A fastening bolt 24a is provided at the tip of the fastening belt 20a, and an insertion hole 26b for the fastening bolt 24a is provided in the end plate 18b. Similarly, a fastening belt 20b extending toward the end plate 18a along the periphery of the stacked body 16 is attached to the end plate 18b. A fastening bolt 24b is provided at the tip of the fastening belt 20b, and an insertion hole 26a for the fastening bolt 24b is provided in the end plate 18a.
[0024]
The tip of a fastening bolt 24b extending from the end plate 18b is inserted into the insertion hole 26a of the end plate 18a, and a fastening nut 28b is attached to the fastening bolt 24b. Similarly, a tip of a fastening bolt 24a extending from the end plate 18a is inserted into the insertion hole 26b of the end plate 18b, and a fastening nut 28a is attached to the fastening bolt 24a.
[0025]
Thus, the tightening nuts 28a and 28b and the tightening bolts 24a and 24b are securely tightened, so that the periphery of the laminate 16 is firmly tightened by the end plates 18a and 18b and the tightening belts 20a and 20b. A clamping pressure is applied between the heat radiating metal plates 14 a and 14 e at both outer ends of the body 16. Accordingly, a tightening pressure is applied to each lithium ion battery 12a, 12b, 12c, 12d via the heat radiating metal plates that are in contact with both side surfaces of the casing. As the clamping pressure, in the case of the lithium ion battery having the above dimensions, for example, several hundred N can be used. The clamping pressure is preferably increased or decreased in consideration of variations in the characteristics of the active material inside the lithium ion battery.
[0026]
In this way, open-circuit voltage is obtained by connecting four lithium ion batteries 12a, 12b, 12c, and 12d in series in four stages while applying clamping pressure to the laminate 16 using a pair of end plates 18a and 18b. A lithium ion battery pack 10 of about 14.4V is configured. The lithium ion assembled battery 10 can be attached to a vehicle using the attachment holes 22 provided in the end plates 18a and 18b, and an open end voltage of about 14.4V can be used as a starter power source.
[0027]
Since both sides of each lithium ion battery 12a, 12b, 12c, 12d are in contact with metal heatsinks 14a, 14b, 14c, 14d, 14e whose surfaces are insulated, each lithium ion battery 12a, 12b , 12c and 12d are not electrically short-circuited, heat generated by the battery action can be released, and heat dissipation characteristics can be improved.
[0028]
In addition, a tightening pressure is applied to both sides of the case of each lithium ion battery 12a, 12b, 12c, 12d, and in the above example, a tightening pressure of several hundred N is applied. The cycle characteristics of the lithium ion battery can be improved.
[0029]
As one of the mechanisms for improving the cycle characteristics of the lithium ion battery by suppressing the swelling of the housing, it can be considered as follows. As described above, in the lithium ion battery, the casing expands when charging and discharging are repeated. If the lateral width of the lithium ion battery is 25 mm, the lateral width may increase by 1-2 mm. This swelling can be considered to be caused by gas generated by the battery reaction. When this gas remains in the gap between the electrode body-separator-electrode body stacks, the gap between the electrode body and the electrode body widens and the battery characteristics and cycle characteristics deteriorate. Here, pressure is applied to both sides of the casing to suppress the expansion of the casing, and in turn suppress the expansion of the stack of electrode body-separator-electrode body, and thereby the generated gas is removed from the electrode body-separator-electrode body. It is possible to prevent the gap between the electrode bodies from being widened by discharging the gap between the stacked layers toward the dead space inside the casing. Thus, the cycle characteristics of the lithium ion battery are improved.
[0030]
【The invention's effect】
According to the lithium ion assembled battery for vehicles according to the present invention, the cycle characteristics of the lithium ion battery can be improved. According to the lithium ion assembled battery for vehicles according to the present invention, the heat dissipation characteristics can be improved.
[Brief description of the drawings]
FIG. 1 is a perspective view of a lithium ion assembled battery according to an embodiment of the present invention.
FIG. 2 is a side view of a lithium ion assembled battery according to an embodiment of the present invention.
FIG. 3 is a diagram showing a configuration of a lithium ion battery.
FIG. 4 is a development view of a battery laminated roll body of a lithium ion battery.
FIG. 5 is a perspective view showing an example of a metal heat radiating plate whose surface is subjected to insulation treatment in the embodiment according to the present invention.
FIG. 6 is a perspective view showing a metal heat radiating plate in another embodiment.
[Explanation of symbols]
10 Lithium ion battery pack, 12, 12a, 12b, 12c, 12d Lithium ion battery, 14a, 14b, 14c, 14d, 14e, 60, 62 Surface heat-insulated metal heat sink, 16 laminate, 18a, 18b End plate, 20a, 20b Clamping belt, 24a, 24b Clamping bolt, 26a, 26b Hole for insertion, 28a, 28b Clamping nut, 30 Housing, 32 lid, 34 Battery laminated roll body, 40, 40a, 40b, 40c, 40d Positive electrode extraction part, 42, 42a, 42b, 42c, 42d Negative electrode extraction part.

Claims (4)

In a vehicle lithium-ion assembled battery that combines a plurality of box-type lithium ion batteries into an assembled battery and supplies power to the vehicle equipment,
A plurality of lithium-ion batteries that are provided with a flat box-shaped housing made of metal and arranged side by side facing each other at an interval;
A plurality of heat-dissipating metal plates arranged in contact with both side surfaces of each lithium ion battery and having an insulating treatment on the surface;
A pair of end plates provided at both outer ends of a laminate in which a plurality of lithium ion batteries and a plurality of heat dissipation metal plates are alternately laminated;
A restraining means for applying a restraining force to both outer ends of the pair of end plates, and applying a clamping pressure to both outer ends of the laminate;
Including
The heat dissipating metal plate has a plurality of heat dissipating through holes in a direction along the width direction of the side surface of the lithium ion battery defined by the height and width in the middle of the plate thickness. battery. In the vehicle lithium ion assembled battery according to claim 1,
The lithium ion battery for vehicles, wherein the heat dissipating metal plate is an aluminum plate having an alumite treatment on the surface. In the vehicle lithium ion assembled battery according to claim 1,
The heat dissipation metal plate is a metal plate having an insulating resin film formed on a surface thereof. In the vehicle lithium ion assembled battery according to claim 1,
The heat radiation metal plate is a metal plate having a ceramic film formed on a surface thereof.

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