JP3288448B2 - Non-aqueous electrolyte battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealed nonaqueous electrolyte battery having an explosion-proof structure.

[0002]

SUMMARY OF THE INVENTION The present invention provides a wound positive electrode, a separator,
In a sealed nonaqueous electrolyte battery having an electrode group consisting of a negative electrode, by disposing an electrode pressing plate made of a thermosetting resin, overcharge, short circuit, or explosive rupture that occurs at the time of heating can be prevented. It was done.

[0003]

2. Description of the Related Art Recently, secondary batteries using non-aqueous electrolytes such as lithium batteries and lithium ion batteries have been widely used in portable electronic devices and the like.

[0004] Incidentally, in the above-mentioned battery, the power generation element housed in the battery undergoes a chemical change to increase the internal pressure, which may cause explosive burst.

[0005] For example, a non-aqueous electrolyte battery such as a lithium secondary battery is supplied with a current higher than usual to cause a so-called overcharged state, a short-circuit state due to misuse, a large current flow, or an erroneous use. When heated, the electrolyte in the power generating element may be decomposed and gas may be generated.These gases fill the battery, the pressure inside the battery increases, and finally the battery It may explode and burst.

Therefore, conventionally, in order to prevent the explosive rupture of the battery as described above, as shown in FIG. 2, a safety valve for explosion proof is provided on the upper end side of an outer can also serving as a negative electrode terminal accommodating a power generating element. Equipment is provided (U.S.A.
9-15398).

For example, the safety valve device shown in FIG. 2 is provided at the upper end portion of the outer can 1, that is, at the sealing lid 2, and has a lid plate 4 having a valve hole 3 formed therein, and a gas vent hole 5. The cover plate 4 is constituted by a bent edge 6 and a dish-shaped terminal plate 7 to be caulked.

A flexible thin plate 8 whose peripheral edge is sandwiched between the lid plate 4 and the dish-shaped terminal plate 7 or the like and always closes the valve hole 3, wherein the flexible thin plate 8 is It is composed of a composite member with a synthetic resin layer 82. 10 is
The blade piece opposes the flexible thin plate 8, and is formed by bending a part of the terminal plate 7 inward.

When the internal pressure of the battery rises due to overcharging or the like, and reaches a predetermined pressure, the flexible thin plate 8 is broken, and the gas in the battery is released from the gas vent hole 5 through the vent hole 5 through the valve hole 3 through the safety valve. Explosive rupture of the battery is prevented beforehand.

[0010]

However, even if such a safety valve device is used, a battery having an electrode group consisting of a wound positive electrode 11, a separator 12, and a negative electrode 13 as shown in FIG. When the electrode group is deformed by the internal pressure, and the valve hole 3 and the gas vent hole 5 are closed by the electrode group, gas is accumulated and the internal pressure increases, and the battery may explode and burst.

[0011] The present invention has been made in view of the above points, and its object is to provide an overcharge, a short circuit,
An object of the present invention is to provide a nonaqueous electrolyte battery that can prevent explosive rupture that occurs during heating.

[0012]

According to the present invention, in a sealed nonaqueous electrolyte battery having an electrode group consisting of a wound positive electrode, a separator and a negative electrode, an electrode made of a thermosetting resin is provided on the electrode group. A battery having a holding plate is provided.

In a conventional sealed nonaqueous electrolyte battery having a wound electrode group, the battery sometimes explosively bursts during overcharge, short circuit, or heating. This is because when the decomposition gas of the electrolytic solution is discharged into the atmosphere from the valve hole 3 or the gas vent hole 5, the electrode group is deformed by the internal pressure of the decomposition gas, and the electrode group is connected to the valve hole 3 or the gas vent hole 5. It was found that the cells clogged, gas accumulated and the internal pressure increased, leading to explosive rupture of the battery.

As a result of examining a method of suppressing deformation of the electrode group at the time of generation of the decomposition gas and preventing blockage of the valve hole 3 and the gas vent hole 5 by the electrode group, an electrode pressing plate made of a specific material was arranged. By fixing the group, when the safety valve is activated in the event of abnormal heat generation, abnormal gas generation, etc., the gas is smoothly dissipated outside the battery can, and it is possible to secure the safety of the battery without causing a phenomenon such as rupture. Was.

In the present invention, the selection of the material of the electrode pressing plate is extremely important.

That is, the material of the electrode pressing plate must be a thermosetting resin. The present inventors have studied various materials including a thermoplastic super heat-resistant resin, and found that a remarkable effect is exhibited only when the above-mentioned thermosetting resin is used.

For example, when the above-mentioned thermoplastic super heat-resistant resin was used, there was no problem in terms of electrical insulation. However, in the case of abnormal heat generation, the resin was deformed and lost its function as a holding plate. The result was that the probability of rupture of the battery can was high.

On the other hand, metal materials, ceramic materials and the like were also examined, but the former had a problem in terms of electrical insulation, and the latter had problems in moldability and cost. The thermosetting resin referred to in the present invention is not particularly limited, but phenol resins, unsaturated polyester resins, melamine resins, epoxy resins, for example, are shown.
Alkyd resins, urea resins and the like can be mentioned.

[0019] If necessary, the thermosetting resin may be reinforced with a reinforcing material such as glass fiber or talc.

In the present invention, in order to further ensure safety, other means such as arranging a pipe at the center of the electrode group may be used at all.

The present invention is effective regardless of the shape of the battery,
The present invention can be applied to batteries having a cylindrical shape, a flat elliptical shape, and other various shapes.

As described above, according to the configuration of the present invention,
Since the electrode group is fixed by the electrode pressing plate made of a thermosetting resin, even if the internal pressure in the battery rises due to overcharge, short circuit, or heating, the electrode group does not deform, and the valve hole 3 and gas The vent hole 5 is closed by the electrode group, and gas can be prevented from accumulating and increasing the internal pressure to prevent the battery from exploding.

[0023]

Next, an embodiment of the present invention will be described with reference to FIG.

The nonaqueous electrolyte battery according to this embodiment is shown in FIG.
As shown in the figure, an electrolytic solution, a cylindrical outer can in which a power generation element composed of an electrode group is housed, and a sealing lid provided with a safety valve provided at an upper end portion of the outer can, the upper part of the electrode group Is provided with an electrode pressing plate 15 made of a thermosetting resin.

Hereinafter, a description will be given based on experimental results of a specific battery.

As a positive electrode plate, a conductive material and a binder were added to a composite oxide LiMnO ₂ of lithium and manganese, applied to an aluminum substrate, dried and formed into a sheet, and a metal lithium sheet was used as a negative electrode plate as it was.
A wrap-around electrode group was formed by interposing a polyethylene microporous film as a separator.

Next, the electrode group in which the pipe was arranged at the center was housed in a stainless steel outer can, and an electrode holder made of phenol resin was arranged on the electrode group, which was caulked and sealed, and the outer diameter was 17 m.
m, a height of 50 mm, and a capacity of 700 mAh were prepared for a cylindrical example battery. The electrolyte used was a solution in which a solute of 1 mol of lithium phosphofluoride was dissolved in a mixed solvent of propylene carbonate and dimethoxyethane.

At the same time, as a comparative example, a battery exactly the same as that of the example except that the electrode pressing plate was not used was produced.

Each of the produced batteries is charged,
A heating test was performed on a hot plate at 250 ° C.

As a result, in the battery of the embodiment, 20
In all cases, gas due to decomposition of the electrolyte gently escaped from the safety valve, and safety was ensured. When the battery after the test was disassembled and examined, no evidence of deformation was found in the electrode group. The phenol resin-made electrode pressing plate was exposed to a high temperature of 400 to 500 ° C. at the maximum in the heating test, but no deformation such as cracking was observed.

On the other hand, in the battery of the comparative example, explosive rupture occurred in three of the twenty batteries, and the sealing lid and the electrode group scattered from the outer can. Further, when the battery which did not undergo explosive rupture was disassembled and examined, partial blockage of the valve hole and the gas vent hole due to the deformation of the electrode group was all observed.

[0032]

According to the present invention constructed as described above, the deformation of the electrode group due to the internal pressure of the decomposition gas of the electrolytic solution is suppressed, and the valve hole and the vent hole are not closed by the electrode group, so that the gas is accumulated. Without this, the gas is smoothly diffused out of the battery via the safety valve, and the safety of the battery at the time of overcharge, short circuit or heating can be ensured.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a battery having a safety structure according to an embodiment of the present invention.

FIG. 2 is a sectional view of a conventional battery.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 outer can 2 sealing lid 3 valve hole 4 lid plate 5 gas vent hole 6 bent edge 7 terminal plate 8 flexible thin plate 9 insulating packing 10 cutting blade 11 positive electrode plate 12 separator 13 negative electrode plate 14 pipe 15 electrode pressing plate

Continuing from the front page (72) Inventor Katsuhiko Inoue 1-3-1, Yoko, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Asahi Kasei Kogyo Co., Ltd. (72) Inventor Yoshiaki Azami 3-4-1, Minamishinagawa, Shinagawa-ku, Tokyo TOSHIBA Within Battery Co., Ltd. (72) Inventor Hiroyoshi Nose 3-4-1-10 Minamishinagawa, Shinagawa-ku, Tokyo Toshiba Battery Co., Ltd. (56) References Japanese Utility Model 1-150372 (JP, U) (58) Field (Int.Cl. ⁷ , DB name) H01M 10/40 H01M 2/12 101 H01M 6/16

Claims (1)

(57) [Claims] 1. A sealed nonaqueous electrolyte battery having an electrode group consisting of a wound positive electrode, a separator and a negative electrode.
A battery, comprising: an electrode pressing plate made of a thermosetting resin disposed on a group .