JPH09306445A - Organic electrolytic battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery which holds superior air tightness for a long time and has high reliability by using one of specific copolymer resins or mixtures of these resins for a sealing gasket for sealing between a positive electrode can and a negative electrode cup. SOLUTION: For example, a coin-shaped lithium battery is so formed that a negative active material 1 composed of lithium, etc., and a positive electrode mix 2 composed of manganese dioxide, or the like are arranged opposed to each other via a separator 4, and a positive electrode can 3 and a negative electrode cup 5 are sealedly fitted to each other via a sealing gasket 6. This gasket 6 is composed of either one of tetrafluoroethylene-ethylene copolymer resin, tetrafluoroethylene-perfluoroalkoxyethylene copolymer resin, or a mixture of tetrafluoroethylene-ethylene copolymer resin and tetrafluoroethylene- perfluoroalkoxyethylene copolymer resin. All of them are superior in elasticity, adhesion, and formability for a long time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electrolyte battery, and more specifically, an organic electrolyte in which a negative electrode active material and a positive electrode mixture are opposed to each other with a separator interposed therebetween and sealed in a battery can via a sealing gasket. It relates to an electrolyte battery.

[0002]

2. Description of the Related Art In recent years, the development of small cordless electronic devices such as electronic notebooks, electronic calculators, and mobile phones has been remarkable, and these power supplies have long life, high voltage, high energy density and small size. The organic electrolyte battery such as a coin-type lithium battery is often used. The structure of a coin-type lithium battery, which is an example of this organic electrolyte battery, will be described with reference to FIG.

FIG. 1 is a schematic side sectional view of a coin type lithium battery. A disk-shaped negative electrode active material 1 made of lithium or a lithium alloy is housed in a negative electrode cup 5, and manganese dioxide, fluorinated graphite, or the like is mixed with a conductive material or a binder to form a pellet-shaped positive electrode. Mixture 2
Are stored in the positive electrode can 3. The negative electrode active material 1 and the positive electrode mixture 2 are disposed to face each other with the separator 4 interposed therebetween, and the positive electrode can 3 and the negative electrode cup 5 are hermetically sealed by fitting through the sealing gasket 6. The sealing gasket 6 also serves to prevent moisture from entering the battery can because the negative electrode active material 1 such as lithium reacts with moisture to deteriorate electrical characteristics such as closed-circuit voltage characteristics and capacity preservation. There is. Conventionally, as a constituent material of the sealing gasket 6, a polyolefin resin such as polypropylene resin or polyethylene resin, which is relatively inexpensive and easy to injection-mold, or has a large water repellency, and the positive electrode can 3 or the negative electrode cup 5 is used. A fluorine-based resin such as polytetrafluoroethylene resin, which has a high adhesiveness with the metal constituting the, is used.

However, the sealing gasket 6 made of polyolefin resin is used for the positive electrode can 3 and the negative electrode cup 5.
Since the adhesiveness with the metal constituting the above and the elasticity of the polyolefin resin itself are small and the elasticity deteriorates over time, the airtightness between the positive electrode can 3 and the negative electrode cup 5 is maintained for a long time. It was inadequate. As a means to improve this, there is a method of supplementing a sealing agent such as asphalt or chlorosulfonated polyethylene resin, but since these sealing agents have adhesiveness, a lot of man-hours are required in the manufacturing process and productivity is increased. It was one of the factors that hindered it.

Further, if the sealing gasket 6 is made of a fluorine-based resin, the adhesion and elasticity with the metal forming the positive electrode can 3 and the negative electrode cup 5 are large, and the space between the positive electrode can 3 and the negative electrode cup 5 is large. Although it is possible to have a sufficiently satisfactory performance for maintaining the airtightness, there is a problem that it is difficult to mold a complicated shape by injection molding and a desired shape cannot be obtained.

[0006]

An object of the present invention is to provide a sealing gasket material that maintains good airtightness for a long period of time,
An object is to provide an organic electrolyte battery having high reliability.

[0007]

In order to solve the above problems, in the organic electrolyte battery of the present invention, the sealing gasket has a tetrafluoroethylene / ethylene copolymer resin or a tetrafluoroethylene / perfluoroalkoxyethylene copolymer resin. Or a mixture of a tetrafluoroethylene / ethylene copolymer resin and a tetrafluoroethylene / perfluoroalkoxyethylene copolymer resin.

The action of the above means is as follows: tetrafluoroethylene / ethylene copolymer resin, tetrafluoroethylene /
Both the perfluoroalkoxyethylene copolymer resin and the mixture of the tetrafluoroethylene / ethylene copolymer resin and the tetrafluoroethylene / perfluoroalkoxyethylene copolymer resin have long-term elasticity and Both ethylene which constitutes the polymer resin and perfluoroalkoxyethylene which constitutes the tetrafluoroethylene / perfluoroalkoxyethylene copolymer resin have an effect of increasing the adhesion between the positive electrode can and the metal constituting the negative electrode cup. Therefore, the airtightness between the positive electrode can and the negative electrode cup can be maintained for a long period of time. Also, the moldability is good,
A sealing gasket having a desired shape can be easily molded by injection molding.

[0009]

[Examples] The following are specific examples of tetrafluoroethylene / ethylene copolymer resin, tetrafluoroethylene / perfluoroalkoxyethylene copolymer resin, tetrafluoroethylene / ethylene copolymer resin and tetrafluoroethylene.・ Three types of sealing gaskets of three types of mixture with perfluoroalkoxyethylene copolymer resin and polypropylene resin, which is one example of polyolefin resin conventionally used as a comparative example, were prepared by injection molding. A coin-shaped lithium battery, which is an example of an organic electrolyte battery, was produced by using each of the batteries. Then, as a method for evaluating the airtightness of the sealing gasket, a coin-type lithium battery made of four kinds of sealing gaskets is left in an atmosphere of a temperature of 60 ° C. and a relative humidity of 90%, and the discharge capacity, the closed circuit voltage, the internal resistance, and the leakage of liquid. The time-dependent changes in the number of occurrences were compared.

First, Table 1 shows the change with time in discharge capacity.
The number of samples is 10, and the numbers in the table are average values.

[0011]

[Table 1]

[0012] In Table 1, the deterioration rate of 100 days after the production was examined, and the tetrafluoroethylene / ethylene copolymer resin was -7.5%, and the tetrafluoroethylene / perfluoroalkoxyethylene copolymer was The resin content was -8%, and the mixture content of tetrafluoroethylene / ethylene copolymer resin and tetrafluoroethylene / perfluoroalkoxyethylene copolymer resin was -7.9%. The value was -17.1%.

Next, Table 2 shows changes with time of the closed circuit voltage. The closed circuit voltage is −10 ° C. and the load resistance is 50
It is measured after discharging at 0Ω for 15 seconds.
The number of samples is 20, and the numbers in the table are average values.

[0014]

[Table 2]

In Table 2, the deterioration rate after 50 days from the time of production is examined. The tetrafluoroethylene / ethylene copolymer resin is -4.5%, and the tetrafluoroethylene / ethylene tetrafluoride
Perfluoroalkoxy ethylene copolymer resin-
4.5%, a mixture of a tetrafluoroethylene / ethylene copolymer resin and a tetrafluoroethylene / perfluoroalkoxyethylene copolymer resin was -4.7%, whereas a polypropylene resin of Comparative Example It was -7.3%.

Next, Table 3 shows changes in internal resistance over time. The internal resistance was measured at 20 ° C. by the sine wave AC method (1 KHz). The number of samples is 20, and the numbers in the table are average values.

[0017]

[Table 3]

In Table 3, looking at the rate of increase after 50 days from the time of production, the tetrafluoroethylene / ethylene copolymer resin was + 50%, and the tetrafluoroethylene / perfluoroalkoxyethylene copolymer resin was + 50%. Is +4
8.4%, + 50.8% for a mixture of tetrafluoroethylene / ethylene copolymer resin and tetrafluoroethylene / perfluoroalkoxyethylene copolymer resin, whereas +92 for the polypropylene resin of Comparative Example. It was 0.1%.

Next, Table 4 shows the changes over time in the number of leaks generated. The number of liquid leaks was visually checked. The number of samples is 20 each.

[0020]

[Table 4]

In Table 4, for the polypropylene resin of the comparative example, 1/20 after 30 days, 2/20 after 40 days, and 6/2 after 50 days.
Although leakage was observed at a rate of 0, tetrafluoroethylene / ethylene copolymer resin, tetrafluoroethylene / perfluoroalkoxyethylene copolymer resin, tetrafluoroethylene /
No liquid leakage was observed in any of the mixture of the ethylene copolymer resin and the tetrafluoroethylene / perfluoroalkoxyethylene copolymer resin.

As is clear from Tables 1 to 4, as a sealing gasket material for organic electrolyte batteries, tetrafluoroethylene / ethylene copolymer resin, tetrafluoroethylene / perfluoroalkoxyethylene copolymer resin, tetrafluoride are used. Any of the mixture of ethylene / ethylene copolymer resin and tetrafluoroethylene / perfluoroalkoxyethylene copolymer resin has discharge capacity, closed circuit voltage, internal resistance and liquid leakage more than those of polypropylene resin used conventionally. The time-dependent changes in the number of occurrences were all significantly improved, and it became clear that good airtightness was maintained for a long time. Also,
The shape of the sealing gasket produced in this example is tetrafluoroethylene / ethylene copolymer resin, tetrafluoroethylene / perfluoroalkoxyethylene copolymer resin, tetrafluoroethylene / ethylene copolymer resin and tetrafluoroethylene / perfluoro resin. Although any of the mixtures with the alkoxyethylene copolymer resin could be easily injection-molded, injection molding was difficult with a fluororesin such as polytetrafluoroethylene resin.

[0023]

According to the organic electrolyte battery of the present invention, since the airtightness between the positive electrode can and the negative electrode cup can be maintained for a long time, an organic electrolyte battery having high reliability can be provided. .

[Brief description of drawings]

FIG. 1 is a schematic side sectional view of a coin type lithium battery.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Negative electrode active material, 2 ... Positive electrode mixture, 3 ... Positive electrode can, 4 ... Separator, 5 ... Negative electrode cup, 6 ... Seal gasket

Claims (3)

[Claims] 1. An organic electrolyte battery in which a negative electrode active material and a positive electrode mixture are opposed to each other with a separator interposed therebetween and which is hermetically sealed in a battery can via a sealing gasket, wherein the sealing gasket is tetrafluoroethylene / ethylene. An organic electrolyte battery, characterized by being formed of a copolymer resin. 2. The organic electrolyte battery according to claim 1, wherein the sealing gasket is formed of tetrafluoroethylene / perfluoroalkoxyethylene copolymer resin. 3. The sealing gasket is formed of a mixture of a tetrafluoroethylene / ethylene copolymer resin and a tetrafluoroethylene / perfluoroalkoxyethylene copolymer resin. 1. The organic electrolyte battery according to 1.