JP3649000B2 - Secondary battery for large current discharge - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a secondary battery for discharging a large current used as a power source for an electric vehicle or the like.
[0002]
[Prior art]
Conventionally, as a secondary battery for large current discharge used as a power source for an electric vehicle or the like, an assembled battery in which a large number of single cells (for example, 40 to 100) are connected in series is used, and a large current (for example, 60 to 200) is used. Ampere) is washed away. In general, since there is an electric resistance of about 2 milliohms at the positive electrode output terminal of the unit cell, the positive output terminal of the assembled battery alone is 80 to 200 milliohms, resulting in a potential difference of 4.8 to 40V. It was. However, in order to reduce this potential difference, for example, if the conduction cross-sectional area of the output terminal is increased, there is a problem that the weight increases.
[0003]
[Problems to be solved by the invention]
The present invention has been made in view of the above problems, and an object of the present invention is to provide a secondary battery for large current discharge in which the electrical resistance of an output terminal is reduced while suppressing an increase in weight.
[0004]
[Means for Solving the Problems]
In a first aspect of the present invention, an electrode group including positive and negative electrodes and a separator and an electrolytic solution are accommodated in a metal battery can having an open end, and an insulating gasket is provided at the open end. A metal sealing lid is caulked, and the metal sealing lid extends from the inside of the battery can to the outside, a dish-shaped lid case made of an aluminum-based material, an aluminum thin plate-shaped safety valve, and an iron-based material. A lid cap made of metal is overlapped in order and welded integrally, and serves as an output terminal of one electrode of the electrode group.
According to a second invention, in the first invention, a periphery of the metal sealing lid is caulked with a periphery of the lid cap made of the iron-based material and a periphery of the dish-shaped lid case made of the aluminum-based material. In addition, the aluminum-based material dish-shaped lid case, the aluminum thin plate-shaped safety valve, and the iron-based material lid cap are integrally welded at the flange portion inside the caulked portion of the peripheral edge. It is characterized by that.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
1. Production of positive electrode Lithium manganate having an average particle diameter of 10 microns, carbon powder having an average particle diameter of 3 microns, and polyvinylidene fluoride (trade name: KF # 120, manufactured by Kureha Chemical Industry Co., Ltd.) as a binder. Then, it is dispersed in N-methyl-2-pyrrolidone as a solvent and mixed to prepare a slurry. This slurry is applied to both surfaces of an aluminum foil having a thickness of 20 microns as a current collector, dried, and then pressed to be integrated. Then, the width | variety was cut | disconnected to 94 mm and the strip-shaped positive electrode was produced.
[0006]
2. Preparation of negative electrode Carbon particles having an average particle diameter of 20 microns and polyvinylidene fluoride (trade name: KF # 120, manufactured by Kureha Chemical Industry Co., Ltd.) as a binder were added to N-methyl-2-pyrrolidone as a solvent. Add and mix to make slurry solution. This slurry is applied to both sides of a copper foil having a thickness of 10 microns as a current collector, dried, and then pressed to be integrated. Then, the width | variety was cut | disconnected to 94.5 mm and the strip-shaped negative electrode was produced.
[0007]
3. As shown in FIG. 1, from the inside to the outside of the battery can 1, a dish-like lid case 2 made of aluminum, a thin safety valve 3 made of aluminum, and a lid made of nickel-plated iron The caps 4 are overlapped in order, and the peripheral edge of the lid cap 4 and the peripheral edge of the lid case 2 are caulked, and the three members are spot welded 7 having a diameter of 3 mm at four locations on the flange 6 inside the caulking part 5 of the peripheral edge. Thus, the sealing lid 10 was produced. Note that the vent 8 provided in the lid case 2 and the lid cap 4 is for rupturing and exhausting the thin safety valve 3 when the battery internal pressure rises above. Further, a ring-shaped valve presser 9 made of butyl rubber is provided to seal between the lid case 2 and the thin plate-shaped safety valve 3.
[0008]
4). Assembling the Battery The positive electrode and the negative electrode are combined and wound through a separator made of a polyethylene porous film having a thickness of 25 microns and a width of 100 mm to produce the electrode group 11. This electrode group 11 is inserted into a metal bottomed cylindrical battery can 1 having an open end, the sealing lid 10 and the positive lead plate 12 of the electrode group 11 are electrically connected, and a non-aqueous electrolyte Inject. Next, the sealing lid 10 was caulked and attached to the open end of the battery can 1 via an insulating gasket 13 to produce a cylindrical secondary battery having a diameter of 40 mm and a height of 114 mm.
[0009]
5. Measurement of electrical resistance of sealing lid As a result of measuring the electrical resistance between the lid case of the sealing lid and the lid cap for the above-mentioned sealing lid in the present invention and the comparative example in which spot welding is not performed with this sealing lid, The lid case and the lid cap are caulked, but the variation was large, 0.2-3.5 milliohm, whereas in the present invention, the value and the variation were small, 0.10-0.14 milliohm. Reduced.
[0010]
【The invention's effect】
As described above, since the secondary battery for large current discharge according to the present invention can significantly reduce the electrical resistance of the output terminal while suppressing an increase in weight, the electric battery used as an assembled battery in which a large number of single cells are connected in series. It is suitable as a power source for automobiles.
[Brief description of the drawings]
FIG. 1 is a partial sectional view showing an embodiment of the present invention.
[Explanation of symbols]
1 is a battery can, 2 is a lid case, 3 is a safety valve, 4 is a lid cap, 5 is a caulking portion, 6 is a flange portion, 7 is spot welded, 8 is a vent, 9 is a valve presser, 10 is a sealing lid, 11 Is an electrode group, 12 is a lead plate, 13 is a gasket

Claims (2)

In a metal battery can having an open end, an electrode group including a positive electrode, a negative electrode, and a separator and an electrolytic solution are accommodated, and a metal hermetic lid is caulked on the open end via an insulating gasket. And the metal sealing lid, from the inside of the battery can toward the outside, a dish-shaped lid case made of aluminum-based material, an aluminum thin plate-shaped safety valve, and a lid cap made of iron-based material are stacked in order, A secondary battery for large current discharge, which is integrally welded and serves also as an output terminal of one electrode of the electrode group. The periphery of the metal sealing lid is caulked with the periphery of the lid cap made of the iron-based material and the periphery of the dish-shaped lid case made of the aluminum-based material, and inside the caulking portion of the periphery The large current according to claim 1 , wherein the aluminum-based material dish-shaped lid case, the aluminum thin plate-shaped safety valve, and the iron-based material lid cap are integrally welded at the flange portion. Secondary battery for discharge.

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