JP2000090892A - Secondary battery for discharging heavy current - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce electric resistance of an output terminal, suppressing a weight increase of a secondary battery for discharging heavy current to be used as a power source of an electric vehicle. SOLUTION: Within a metallic battery can 1 having an open end, an electrode group 11 including positive and negative electrodes and a separator and electrolytic solution are stored. At the open end, a metallic sealing cover 10 is caulked via an insulating gasket 13. In the sealing cover 10, a metallic dished cover case 2, a thin plate safety valve 3 and a metallic cover cap 4 are successively overlapped from the inside of the battery can 1 toward the outside, and at least the cover case 2 and the cover cap 4 are integrally spot-welded 7 and are used also as an output terminal of one electrode of the electrode group 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field 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]

2. Description of the Related Art Conventionally, as a secondary battery for discharging a large current used as a power source for an electric vehicle or the like, an assembled battery in which a number of cells (for example, 40 to 100) are connected in series is used. (Eg, 60-200 amps). In general, the output terminal of the positive electrode of a unit cell has an electric resistance of about 2 mOhm, so that the output terminal of the positive electrode of the assembled battery alone has a resistance of 80 to 200 mOhm, which is 4.8 to 4 mOhm.
A potential difference of 0 V was generated. However, in order to reduce the 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]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a secondary battery for large current discharge in which the electric resistance of an output terminal is reduced while suppressing an increase in weight. The purpose is to:

[0004]

SUMMARY OF THE INVENTION A first invention of a secondary battery for large current discharge according to the present invention comprises an electrode group including a positive electrode, a negative electrode, a separator and an electrolytic solution in a metal battery can having an open end. And a metal sealing lid is caulked at the open end via an insulating gasket. The sealing lid is a metal dish-shaped lid from inside to outside of the battery can. Case,
A thin plate-shaped safety valve and a metal lid cap are sequentially stacked, and at least the lid case and the lid cap are integrally welded, and also serve as an output terminal of one electrode of the electrode group. And The second invention is
In the hermetic lid, the lid case is formed of an aluminum-based material, and the lid cap is formed of an iron-based material, and also serves as an output terminal of a positive electrode. The current collector of the positive electrode is formed of an aluminum-based material. It is characterized by having been done. According to a third aspect of the present invention, in the sealing lid, a peripheral edge of a lid cap and a peripheral edge of the lid case are caulked, and the welding portion is a flange portion inside a caulked portion of the peripheral edge. I do.

[0005]

Embodiments of the present invention will be described below. 1. Preparation of Positive Electrode Lithium manganate having an average particle size of 10 microns, carbon powder having an average particle size of 3 microns, and polyvinylidene fluoride (trade name: KF # 120, manufactured by Kureha Chemical Industry Co., Ltd.) as a binder Is dispersed in N-methyl-2-pyrrolidone as a solvent and mixed to form a slurry. This slurry is applied to both sides of an aluminum foil having a thickness of 20 μm 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 size 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. It is charged and mixed to prepare a slurry-like solution.
This slurry is applied to both surfaces of a copper foil having a thickness of 10 μm as a current collector, dried, and then integrated by pressing. Thereafter, the width was cut to 94.5 mm to produce a strip-shaped negative electrode.

[0007] 3. 1. Production of Hermetic Lid As shown in FIG. 1, from the inside to the outside of the battery can 1, a dish-shaped lid case 2 made of aluminum, a thin plate-shaped safety valve 3 made of aluminum, and a lid made of nickel-plated iron The caps 4 are stacked one on top of the other,
And the peripheral edge of the lid case 2 are caulked, and the three members are spot welded with a diameter of 3 mm 7 at four locations on the flange portion 6 inside the caulked portion 5 of the peripheral edge to integrate the three members.
0 was produced. In addition, the vent 8 provided in the lid case 2 and the lid cap 4 is for opening and exhausting the thin plate-shaped safety valve 3 when the internal pressure of the battery rises more.
Further, a ring-shaped valve retainer 9 made of butyl rubber is provided to seal the space between the lid case 2 and the thin plate-shaped safety valve 3.

[0008] 4. Assembling the battery Combining the positive and negative electrodes, the thickness is 25 microns,
The electrode group 11 is formed by winding the sheet through a separator made of a porous polyethylene film having a width of 100 mm. The electrode group 11 is inserted into a metal bottomed cylindrical battery can 1 having an open end, and the hermetic lid 10 is electrically connected to the positive electrode lead plate 12 of the electrode group 11. Inject. Next, the open end of the battery can 1 was caulked and attached to the open end of the battery can 1 via an insulating gasket 13 to have a diameter of 40 mm.
And a cylindrical secondary battery having a height of 114 mm was manufactured.

[0009] 5. Electric Resistance Measurement of Sealed Lid The above-described closed lid in the present invention and a comparative example in which spot welding was not performed with this closed lid, the electrical resistance between the lid case and the lid cap of the closed lid was measured. Although the lid case and lid cap are caulked,
In contrast to the large variation of 0.2 to 3.5 mOhm, the present invention has a small value and small variation of 0.10 to
It could be reduced to 0.14 mOhm.

[0010]

As described above, the secondary battery for large current discharge according to the present invention can greatly reduce the electric resistance of the output terminal while suppressing an increase in weight, so that a large number of cells are connected in series. It is suitable as a power source for an electric vehicle or the like used as an assembled battery.

[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 caulked portion, 6 is a flange portion, 7 is spot welding, 8 is a vent, 9 is a valve holder, 10 is a sealing lid, 11 Is an electrode group, 12 is a lead plate, and 13 is a gasket.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kotaro Kobayashi 2-8-7 Nihonbashi Honcho, Chuo-ku, Tokyo Inside Shin-Kobe Electric Co., Ltd. (72) Inventor Mitsuru Koseki 2-87 Nihonbashi Honcho, Chuo-ku, Tokyo Shin Kobe Electric Co., Ltd. F term (reference) 5H011 AA04 CC06 DD13 DD15

Claims (3)

[Claims] 1. A metal battery can having an open end.
A negative electrode, an electrode group including a separator, and an electrolytic solution are housed, and a metal hermetic lid is caulked at the open end via an insulating gasket. , A metal dish-shaped lid case, a thin plate-shaped safety valve, and a metal lid cap are sequentially stacked, and at least the lid case and the lid cap are integrally welded, and one of the electrode groups A secondary battery for large current discharge, which also serves as an output terminal of the electrode. 2. The closed lid, wherein a lid case is formed of an aluminum-based material and the lid cap is formed of an iron-based material, respectively, and also serves as an output terminal of a positive electrode, and the positive electrode has a current collector. 2. The secondary battery according to claim 1, wherein the secondary battery is formed of an aluminum-based material. 3. The sealing lid according to claim 1, wherein a peripheral edge of a lid cap and a peripheral edge of the lid case are caulked, and the welding portion is a flange portion inside a caulking portion of the peripheral edge. The secondary battery for large current discharge according to claim 1 or 2.