JP2000067824A - Battery pack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery pack that prevent its electrolyte from leaking outside while introducing the air sufficiently from the outside into air batteries received inside. SOLUTION: In this battery pack 1 multiple air batteries 2 wherein air holes 7 are formed in their positive electrode cans 5 are stored in an outer can 3 having air introduction holes 9, and an insulating sheet 4 formed of a porous fluorine-contained resin film having a vacancy rate of 20-60% is arranged between the air batteries 2 and the outer can 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable battery pack used as a drive power source for portable electronic equipment, and more particularly to a battery pack using an air battery.

[0002]

2. Description of the Related Art With the spread of portable electronic devices in recent years, various demands have arisen for portable driving power supplies for the portable electronic devices. In particular, for a battery used as a power supply for driving, a so-called high energy density battery that is lighter, smaller, and has a longer life is desired.

As a high energy density battery, an air battery has recently been widely used as a power source for driving small electronic devices such as a pager and a hearing aid. The air battery is configured such that an air electrode and a negative electrode active material that constitute a positive electrode are housed in a metal positive electrode can having an air hole for taking in oxygen in the air that is a positive electrode active material from the outside,
It has a structure that is sealed by a metal negative electrode cup. As described above, the air battery uses oxygen in the air as the positive electrode active material, so that it is possible to provide a light-weight, large-capacity, high-energy-density driving power supply by itself or by connecting a plurality of battery packs. ing.

[0004] An outer can of a battery pack containing a plurality of air cells as described above is provided with an air intake hole for supplying air to an internal air cell.
For this reason, when the air battery inside the battery pack leaks, the electrolyte of the air battery may leak from the air intake hole formed in the outer can.

In the above-mentioned battery pack, since the outer can is made of metal, if an air battery having a metal positive electrode can and a negative electrode cup is housed inside, the air battery is short-circuited. .

Therefore, in order to prevent the above-mentioned leakage of the electrolytic solution and short circuit of the air battery, a plastic or paper insulating sheet is housed between the metal outer can and the air battery. is there.

[0007]

However, when a plastic insulating sheet is used to insulate the outer can from the air cell, the supply of air to the air cell inside the outer can is obstructed and the battery cannot function as a battery. was there.

When a paper insulating sheet is used to insulate the outer can from the air battery, when the air battery inside the outer can leaks, the electrolyte penetrates the paper sheet and is formed on the outer can. There is a problem that there is a possibility that the air leaks from the air hole.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a battery pack which can sufficiently take in air from the outside and can prevent leakage of an electrolytic solution to the outside of the battery pack.

[0010]

A battery pack according to the present invention, which achieves the above-mentioned object, comprises a plurality of air batteries, each having an air hole formed in a battery can, housed in an outer can having an air intake hole. And an insulating sheet made of a porous fluororesin film having a porosity of 20% to 60% is provided between the air battery and the outer can.

The battery pack according to the present invention having the above-described structure uses a porous fluororesin film having a porosity of 20% to 60% as the insulating sheet, so that the inflow of air into the battery pack is inhibited. In addition, even if a leak occurs in the air battery, leakage to the outside of the outer can is prevented.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of a battery pack according to the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, battery pack 1 according to the present embodiment houses three button-type air batteries 2 (2 a, 2 b, 2 c) that are vertically connected in series, and accommodates these air batteries 2. It comprises a metal outer can 3 and an insulating sheet 4 disposed between the air battery 2 and the outer can 3 to insulate the air battery 2 from the outer can 3. In addition, the air battery 2 housed in the battery pack 1 is not limited to the button-type air battery described above, and may be a coin-type air battery.

As shown in FIG. 1, each air battery 2 has a metal positive electrode can 5 formed in a cylindrical shape with a bottom and an open end.
A negative electrode active material such as zinc, an electrolytic solution such as an aqueous solution of potassium hydroxide, and the like are accommodated therein, and the opening of the positive electrode can 5 is closed by the negative electrode cup 6. The positive electrode can 5 has an air hole 7 formed on the bottom surface thereof for taking in oxygen in the air serving as a positive electrode active material from the outside.

In the air battery 2, the negative electrode cup 6
A protruding portion 8 is formed at a substantially central portion thereof so as to protrude outward. As shown in FIG. 1, when the air battery 2 is connected in series by directly contacting the negative electrode cup 6 of one of the air batteries 2 a with the positive electrode can 5 of the other air battery 2 b as shown in FIG. The protrusion 8 formed on the negative electrode cup 6 is
The bottom surface is in contact with a portion where the air hole 7 is not formed, the air hole 7 is not closed, and the inflow of air into the inside is not hindered.

The outer can 3 is composed of the air battery 2 housed inside.
Is formed with an air intake hole 9 for supplying external air. The air intake hole 9 is formed at substantially the same position as the position where the projection 8 of the negative electrode cup 6 contacts the bottom surface of the positive electrode can 5 and at the position facing the bottom surface of the positive electrode can 5 of the last air cell 2c. In the battery pack 1, if the distance between the air hole 7 and the air intake hole 9 is long, the time that the air entering from the air intake hole 9 reaches the air hole 7 through the inside of the outer can 3 becomes longer, and the air Since the supply is not performed efficiently, the air hole 7 and the air intake hole 9 are provided close to each other.

The insulating sheet 4 is made of an air battery 2 formed by contact between a metal positive electrode can 5 and a metal outer can 3.
To prevent short circuit. As the insulating sheet 4, a porous polytetrafluoroethylene sheet having a porosity of 20% to 60% is used. The porous polytetrafluoroethylene sheet has a high insulating property and a property of not allowing a liquid to pass through gas, so that air can be sufficiently taken into the outer can 3 and the outer package can be formed even when the air battery 2 leaks. Leakage from the can 3 can be prevented. Also, if the porosity of the porous polytetrafluoroethylene sheet is less than 20%, the air is not sufficiently taken in the insulating sheet 4 to perform the discharge efficiently. 20% porosity due to liquid permeation
It is preferably from 60% to 60%.

The insulating sheet 4 is wound in a tube shape, wound around the outer peripheral surface of the air battery 2, and disposed in the outer can 3. When the air battery 2 leaks, the electrolyte sheet may be leaked from the gap between the ends of the insulating sheet 4 wound in a tube shape. .

The insulating sheet 4 has a thickness of 0.03 mm.
乃至 2 mm is used. The insulating sheet 4 has a thickness of 0.
If the thickness is less than 03 mm, the sheet expands during handling, and the porosity changes. If the thickness is more than 2 mm, the volume occupancy in the battery pack 1 increases, and the size of the air battery 2 inserted therein decreases. It is not preferable because the battery capacity is reduced.

[0019]

EXAMPLE A battery pack will be specifically described based on the results of various tests performed on the battery packs of Examples 1 to 5 and Comparative Examples 1 to 3 shown below.

In Examples 1 to 5 used in the test, three button-type air cells and a thickness of 0.1 m
m of an insulating sheet made of a porous polytetrafluoroethylene sheet having a porosity of 20% and 3%, respectively.
The battery packs are 0%, 40%, 50%, and 60%. In Comparative Examples 1 to 3, similarly to Examples 1 to 5, three button-type air batteries were housed inside, and as the insulating sheets, a paper sheet and a thickness of 0.1 were respectively used.
This is a battery pack using a porous polytetrafluoroethylene sheet having a porosity of 10 mm and a porosity of 10%, and a porous polytetrafluoroethylene sheet having a porosity of 70% and a thickness of 0.1 mm.

First, a test was conducted on Example 1 and Comparative Example 1 to check for the occurrence of liquid leakage under certain conditions.
In the test for checking for the occurrence of liquid leakage, ten battery packs were stored in an oven at a temperature of 60 ° C. and a relative humidity of 90% RH for 60 days, and the electrolyte leaked out of the battery pack. The numbers were compared and performed. Table 1 shows the test results.

[0022]

[Table 1]

As shown in Table 1, it was confirmed that no liquid leakage occurred in the battery pack of Example 1. On the other hand, in the battery pack of Comparative Example 1, it was confirmed that liquid leakage occurred in all of the 10 battery packs tested. From this test result, it can be determined that a porous polytetrafluoroethylene sheet is more suitable for an insulating sheet used for a battery pack than a paper sheet that leaks out due to penetration of an electrolytic solution.

Next, a test was conducted on Examples 1 to 5 and Comparative Examples 2 and 3 to determine whether or not liquid leakage occurred and the battery capacity under certain conditions. In a test to check for the occurrence of liquid leakage and the electric capacity, ten battery packs were stored in an oven at a temperature of 60 ° C. and a relative humidity of 90% RH for 60 days. The number of leaked items was compared. Table 2 shows the test results.

[0025]

[Table 2]

As shown in Table 2, Examples 1 to 5
It was confirmed that all of the battery packs had a battery capacity of 600 mAh or more, and no liquid leakage occurred. On the other hand, in the battery pack of Comparative Example 2, no liquid leakage occurred, but the battery capacity was less than 600 mAh and it was confirmed that the battery capacity was insufficient when used as a power supply for driving a portable electronic device. The battery pack of Comparative Example 3
Although the battery capacity exceeded 600 mAh, generation of liquid leakage was confirmed. From this test result, it can be determined that the porous polytetrafluoroethylene sheet used as the insulating sheet of the battery pack preferably has a porosity of 20% to 60%.

[0027]

As described above in detail, according to the battery pack according to the present invention, the insulating sheet for insulating the metal positive electrode can and the outer can of the air battery has a high insulating property and allows the gas to pass through the insulating sheet. The use of a porous fluororesin membrane that does not allow air to pass through allows sufficient intake of air into the outer can and also prevents leakage from the outside of the outer can in the event of leakage of air cells. Can be.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a battery pack.

[Explanation of symbols]

Reference Signs List 1 battery pack, 2 air battery, 3 outer can, 4 insulating sheet, 5 positive electrode can, 6 negative electrode cup, 7 air hole, 8
Protrusion, 9 air intake hole

Claims (5)

[Claims] A plurality of air batteries each having an air hole formed in a battery can are housed in an outer can having an air intake hole, and a porosity between the air battery and the outer can is 20%. To 60
%, Provided with an insulating sheet made of a porous fluororesin film. 2. The battery pack according to claim 1, wherein the air battery is a button battery or a coin battery. 3. The battery pack according to claim 1, wherein the porous fluororesin film is a porous polytetrafluoroethylene film. 4. The battery according to claim 1, wherein the insulating sheet is formed of a tube-shaped porous fluororesin film, and the insulating sheet is wound around a peripheral surface of the air battery overlapped. pack. 5. The battery pack according to claim 4, wherein both ends of the tubular porous fluororesin film are heat-sealed.