JP2004227788A - Lithium ion battery pack for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve cycle characteristics and improve heat radiation characteristics in a lithium ion battery pack for a vehicle. <P>SOLUTION: This lithium ion battery pack 10 includes a laminated body 16 to laminate alternately four lithium ion batteries 12a, 12b, 12c, 12d, and five sheets of metal heat radiation plates 14a, 14b, 14c, 14d, 14e on whose surface an insulating treatment is applied. The respective lithium ion batteries have a metallic flat-box type cabinet, and contacts with both side faces of the respective lithium ion batteries, and the respective metallic heat radiation plates of which the insulating treatment is applied on the surface are arranged. A pair of end plates 18a, 18b, and tightening belts 20a, 20b mounted on the end plates 18a, 18b are installed at a circumference of the laminated body 16, and the end plates 18a, 18b and the tightening belts 20a, 20b are mutually tightened. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a lithium-ion battery assembly for a vehicle, and more particularly to a lithium-ion battery assembly for a vehicle that is formed by combining a plurality of box-shaped lithium-ion batteries.
[0002]
[Prior art]
Conventionally, a nickel-metal hydride battery has been used as a battery for supplying electric power to an electric device or the like mounted on a vehicle. For example, Patent Literature 1 discloses a nickel-metal hydride battery formed by arranging a plurality of rectangular unit batteries in parallel. Nickel-metal hydride batteries have an open-end voltage of about 1.2 V, so that in order to obtain a high voltage required as a power supply for vehicles, the number of series connection stages is increased, which is inconvenient. Therefore, a lithium-ion battery having an open-circuit voltage as high as about 3.6 V has attracted attention.
[0003]
[Patent Document 1]
JP 2001-196103 A
[Problems to be solved by the invention]
Lithium-ion batteries have the characteristic that the open-circuit voltage is about three times higher than that of nickel-metal hydride batteries. For example, when used as a starter power supply that requires an output voltage of about 14.4 V, it is convenient to handle as a single assembled battery by connecting four stages of lithium-ion batteries having an open-end voltage of 3.6 V in series. .
[0005]
Regarding the structure of the assembled battery, in Patent Document 1 described above, in the assembled battery in which the rectangular parallelepiped unit batteries are arranged in parallel so that the side surfaces of the maximum area are overlapped and a cooling medium passage is formed between the unit batteries, There is disclosed an example in which a cooling medium passage is formed by interposing a spacer made of a metal material between facing surfaces between unit cells.
[0006]
However, since a lithium ion battery dislikes moisture due to its electromotive mechanism, a metal housing is used for the battery. In this respect, since there is no such restriction, it is greatly different from a nickel-metal hydride battery generally using a resin housing. That is, from the viewpoint of the battery configuration of the lithium-ion battery, the potential of the metal casing 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 become the same at that point, so that a sufficient open-end voltage as an assembled battery cannot be obtained.
[0007]
Although it is conceivable to perform a laminating process of an insulating film on the front side of each housing, extra cost is required for the insulating process, and if the insulating process has a defect, it does not function sufficiently as a battery pack. In addition, it is conceivable that an insulating plate is interposed between the metal casings. However, generally, the insulator does not have a good thermal conductivity and cannot secure heat radiation characteristics as an assembled battery.
[0008]
Further, the lithium ion battery has a problem of so-called cycle characteristic deterioration in which the number of charge / discharge operations gradually decreases as charge / discharge is repeated. When the charge and discharge are repeated, the housing expands. Therefore, in order to improve the cycle characteristics, pressure is applied to the housing to suppress its deformation. Considering that a battery pack is used, it is more convenient to apply pressure after combining a plurality of lithium ion batteries than to apply pressure to each lithium ion battery. Also in this case, as described above, when a plurality of housings are brought into direct contact with each other and pressure is applied thereto, or pressure is applied to the plurality of housings via a metal plate having good heat dissipation properties, a sufficient open end as a battery pack is obtained. If voltage is not obtained and pressure is applied to a plurality of housings via the insulating plate, sufficient heat radiation characteristics cannot be obtained.
[0009]
An object of the present invention is to solve the problems of the prior art and to provide a lithium ion battery pack for vehicles that can improve the cycle characteristics of a lithium ion battery. Another object is to provide a vehicle lithium-ion battery pack that can improve heat dissipation characteristics.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, a vehicle lithium ion battery according to the present invention is a vehicle lithium ion battery that supplies a power to a vehicle device by combining a plurality of box-type lithium ion batteries to form a battery pack. A plurality of lithium-ion batteries arranged side by side with a space between them, and arranged in contact with both sides of each lithium-ion battery, and the surface is insulated. A plurality of heat dissipating metal plates, a pair of end plates provided on both outer ends of a stacked body 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 Restraining means for applying a force and applying a clamping pressure to both outer ends of each laminate.
[0011]
According to the above configuration, a plurality of lithium ion batteries including a flat box-shaped housing made of metal, and a plurality of heat-dissipating metal plates having a surface subjected to insulation treatment are alternately stacked to form a stacked body. 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 tightening pressure to both outer ends of the stacked body.
Therefore, since the heat-dissipating metal plate whose surface is insulated is arranged between the flat box-shaped housings made of metal, the metal housings are electrically insulated from each other. The open-circuit voltage can be secured, and the heat radiation characteristics can be improved. Further, 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]
Further, it is preferable that the heat-dissipating metal plate is an aluminum plate whose surface is anodized. With the above configuration, it is possible to obtain a lithium ion battery for a vehicle that is lightweight and has good heat dissipation characteristics. Further, the heat dissipation metal plate is preferably a metal plate having an insulating resin film formed on the surface. Further, the heat-dissipating metal plate is preferably a metal plate having a ceramic film formed on the surface.
[0013]
BEST MODE FOR CARRYING OUT 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 battery pack 10, and FIG. 2 is a side view thereof. The lithium-ion battery assembly 10 includes four lithium-ion batteries 12a, 12b, 12c, and 12d, and five metal radiating plates 14a, 14b, 14c, 14d, and 14e, each of which has an insulating surface, alternately stacked. Including the laminated body 16. Around the laminate 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 arranged on the back side of the laminate 16 and appears in the figure). The end plates 18a, 18b and the fastening belts 20a, 20b are fastened to each other as described later.
[0014]
FIG. 3 is a diagram illustrating a 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 housed inside the housing 30. And an electrolytic solution that is impregnated into the battery stack roll body 34.
[0015]
The housing 30 may be, for example, a metal plate having a thickness of about 1 mm formed by drawing into a flat box having a height of about 102 mm, a wide width of about 120 mm, and a narrow width of about 25 mm. it can. If necessary for handling, the outer surface of the housing may be subjected to surface treatment such as insulating coating. The lid 32 is provided with a positive electrode extraction section 40 and a negative electrode extraction section 42 which are insulated from each other. A metal plate 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 resin or ceramic is provided between the lid 32 and the positive electrode extraction section 40 and the negative electrode extraction section 42. Provided.
[0016]
As shown in the developed view of FIG. 4, the battery stack roll body 34 overlaps with a separator 48 sandwiched between two electrode bodies 44 and 46 coated with an active material, and winds this into a roll. Things. One electrode body 44 of the two electrode bodies is made of aluminum foil as a base material, an active material is applied to the surface thereof, and a positive electrode part 50 for extracting electric charges is connected to the aluminum part by welding or the like. The other electrode body 46 is made of a copper foil as a base material, on which an active material is applied, and a negative electrode part 52 for extracting electric charges is connected to a copper part by welding or the like. The battery stack roll body 34 has an electrode body 44, a separator 48, and an electrode body 46 stacked in this order and wound in a roll shape so that the positive electrode part 50 and the negative electrode part 52 protrude into the upper opening of the housing 30. Then, it is housed inside the housing 30, and then the electrolytic solution is injected and permeates between the electrode body 44, the separator 48 and the electrode body 46. The positive electrode part 50 and the negative electrode part 52 of the battery stack roll body 34 are connected to the positive electrode extraction part 40 and the negative electrode extraction part 42 of the lid 32, respectively.
[0017]
The lithium ion batteries 12a, 12b, 12c, 12d are arranged at intervals with their side surfaces facing each other. Here, the side surface refers to a side surface having a larger area among the side surfaces of the flat box-shaped housing. In the above example, the side surface has a height of about 102 mm and a width of about 120 mm. In order to arrange the four lithium ion batteries 12a, 12b, 12c, and 12d in series, the arrangement of the positive electrode extraction section 40 and the negative electrode extraction section 42 is reversed every other cell. can do. That is, the positive electrode extraction section 40b of the lithium ion battery 12b is adjacent to the negative electrode extraction section 42a of the lithium ion battery 12a, and the positive electrode extraction section 40c of the lithium ion battery 12c is adjacent to the negative electrode extraction section 42b of the lithium ion battery 12b. Then, the positive electrode extraction portion 40d of the lithium ion battery 12d is arranged adjacent to the negative electrode extraction portion 42c of the lithium ion battery 12c.
[0018]
Here, if the adjacent 42a and 40b, 42b and 40c, 42c and 40d are connected, the open-end voltage of the four-stage series connection is 3.6 V × 4 between the positive electrode extraction section 40a and the negative electrode extraction section 42d. 14.4V can be taken out.
[0019]
FIG. 5 and FIG. 6 are perspective views showing examples of a metal radiator plate whose surface has been subjected to insulation treatment. The metal heat radiating plate 60 shown in FIG. 5 is obtained by subjecting an aluminum plate having a plate thickness of about 2 to 5 mm and having a flat surface as a base material to anodizing the surface.
It is preferable that the size of the surface in contact with the side surface of the lithium ion battery is 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 is provided with a plurality of through holes 64 for heat radiating, for example, in the width direction in the middle of the aluminum plate thickness. Also in this case, alumite treatment is performed on the surface.
[0020]
Instead of the 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 polyamide imide 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 a 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 as the base material.
[0021]
The metal radiator plate whose surface has been subjected to insulation treatment is arranged 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 a gap between the lithium ion batteries arranged at intervals, and the outer side surfaces of the lithium ion batteries 12a and 12d at both outer ends are provided. Correspondingly, a total of five metal radiators are used, for a total of two.
[0022]
Returning to FIGS. 1 and 2, the surroundings of the end plates 18a and 18b will be described. The end plates 18a and 18b are formed by pressing a metal plate by press working or the like, and are arranged in contact with the metal heat radiating plates 14a and 14e at both outer ends of the laminated body 16. Since the end plates 18a and 18b are plates for fulfilling the function of clamping the laminated body 16, it is preferable to provide appropriate corrugated shapes and ribs so that the clamping pressure can be sufficiently transmitted to the metal radiating plates 14a and 14e. . The end plates 18a and 18b may be provided with mounting holes 22 for attaching a 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 a hole 26b for inserting the fastening bolt 24a is provided on 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 a hole 26a for inserting the fastening bolt 24b is provided in the end plate 18a.
[0024]
The end 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, by tightly tightening between the tightening nuts 28a, 28b and the tightening bolts 24a, 24b, the periphery of the laminated body 16 is securely tightened by the end plates 18a, 18b and the tightening belts 20a, 20b. A clamping pressure is applied between the heat dissipating metal plates 14a and 14e at both outer ends of the body 16. Therefore, a tightening pressure is applied to each of the lithium ion batteries 12a, 12b, 12c, and 12d via the heat dissipating metal plates that come into contact with both side surfaces of the housing.
As the tightening pressure, for example, several hundred N can be used in the case of a lithium ion battery having the above dimensions. It is preferable that the tightening pressure is increased or decreased in consideration of variations in the characteristics of the active material inside the lithium ion battery.
[0026]
As described above, by connecting the four lithium-ion batteries 12a, 12b, 12c, and 12d in four stages in series while applying a tightening pressure to the stacked body 16 using the pair of end plates 18a and 18b, the open-end voltage is reduced. A lithium ion battery pack 10 of about 14.4 V is configured. The lithium-ion battery pack 10 is mounted on a vehicle using the mounting holes 22 provided in the end plates 18a and 18b, and an open-end voltage of about 14.4 V can be used as a starter power supply.
[0027]
Metal radiating plates 14a, 14b, 14c, 14d, and 14e, whose surfaces are insulated, are in contact with both sides of each of the lithium-ion batteries 12a, 12b, 12c, and 12d. , 12c, and 12d are not electrically short-circuited, heat generated by the battery action can be released, and heat radiation characteristics can be improved.
[0028]
Further, a clamping pressure, that is, a clamping pressure of several hundred N in the above example, is applied to both side surfaces of the casing of each of the lithium ion batteries 12a, 12b, 12c, and 12d. Thus, the cycle characteristics of the lithium ion battery can be improved.
[0029]
One of the mechanisms by which the swelling of the housing is suppressed to improve the cycle characteristics of the lithium ion battery can be considered as follows. As described above, in a lithium-ion battery, when charging and discharging are repeated, the housing expands. Assuming that the width of the lithium ion battery is 25 mm, the width may expand by 1-2 mm. This swelling can be attributed to the gas generated by the battery reaction. When this gas remains in the gap between the electrode body, the separator and the electrode body, the distance between the electrode bodies is widened, and the battery characteristics and the cycle characteristics deteriorate. Here, pressure is applied to both side surfaces of the housing to suppress swelling of the housing, and thus to suppress swelling of the electrode body-separator-electrode stack, so that the generated gas is discharged from the electrode body-separator-electrode body. It is possible to discharge from the gap of the lamination to the dead space inside the housing, thereby suppressing an increase in the interval between the electrode bodies. Thus, the cycle characteristics of the lithium ion battery are improved.
[0030]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to the lithium ion battery for vehicles which concerns on this invention, the cycle characteristic of a lithium ion battery can be improved. According to the lithium ion battery for a vehicle according to the present invention, heat radiation characteristics can be improved.
[Brief description of the drawings]
FIG. 1 is a perspective view of a lithium ion battery pack according to an embodiment of the present invention.
FIG. 2 is a side view of the lithium ion battery pack according to the 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 stack roll of a lithium ion battery.
FIG. 5 is a perspective view showing an example of a metal radiator plate having a surface subjected to insulation treatment in the embodiment according to the present invention.
FIG. 6 is a perspective view showing a metal radiator plate according to 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 Metal radiator plate whose surface is insulated, 16 laminate, 18a, 18b End plate, 20a, 20b fastening belt, 24a, 24b fastening bolt, 26a, 26b insertion hole, 28a, 28b fastening nut, 30 housing, 32 lid, 34 battery stack roll, 40, 40a, 40b, 40c, 40d Positive electrode extraction section, 42, 42a, 42b, 42c, 42d Negative electrode extraction section.

Claims (4)

A plurality of box-type lithium-ion batteries are combined to form a battery pack, and in a vehicle lithium-ion battery pack for supplying power to vehicle equipment,
A plurality of lithium-ion batteries having a flat box-shaped housing made of metal, arranged side by side with a space therebetween,
A plurality of heat-dissipating metal plates arranged in contact with both sides of each lithium-ion battery, the surface of which is insulated;
A pair of end plates provided at both outer ends of a stacked body in which a plurality of lithium ion batteries and a plurality of heat dissipation metal plates are alternately stacked,
A restraining means for applying a restraining force to both outer ends of the pair of end plates and applying a tightening pressure to both outer ends of the laminated body. The vehicle lithium-ion battery according to claim 1,
A lithium ion battery for a vehicle, wherein the heat dissipating metal plate is an aluminum plate having a surface anodized. The vehicle lithium-ion battery according to claim 1,
The heat-dissipating metal plate is a metal plate having an insulating resin film formed on a surface thereof. The vehicle lithium-ion battery according to claim 1,
The heat-dissipating metal plate is a metal plate having a ceramic film formed on a surface thereof.

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