JPS5991660A - Organic electrolyte battery - Google Patents

Abstract

PURPOSE:To increase the liquid-leakage resistance and the preservation performance of an organic battery, which has a negative electrode made of a light metal, a positive electrode and an organic electrolyte, by using a sealing agent prepared by adding a vinyl acetate (co)polymer to straight asphalt. CONSTITUTION:A negative electrode 3 is made by pressing and fixing a light metal such as Li to a stainless steel net fused by spot welding to the inner surface of a sealing plate 1 made of an Ni-stainless-steel clad plate and also serving as a negative terminal. A positive electrode 4 is made by molding a positive mixture principally consisting of a positive active material such as MnO2, carbon fluoride or iron sulfide. A separator 6 is placed on an annular seat 5 installed in a battery case 7 also serving as a positive terminal, then impregnated with an organic electrolyte. In a battery with such constitution as above, a sealing agent 9 prepared by adding vinyl acetate or a vinyl acetate copolymer dissolved in an organic solvent to straight asphalt, is applied to desired areas of an annular gasket 8, the case 7 and the sealing plate 1 before being dried.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvement of an organic electrolyte battery using a light metal as a negative material, and aims to improve leakage resistance and storage performance.

Generally, in organic electrolyte batteries that use a light metal as the negative electrode, an annular gasket made of polypropylene that is resistant to organic solvents is placed between the opening of the battery case and the sealing plate, and the opening end of the battery case is tightened inward. A sealing structure is adopted in which an annular gasket is pressed into contact with the open end of the battery case and the peripheral edge of the sealing plate from the button to create a seal.

However, due to scratches on the surface of the battery case and sealing plate, as well as scratches on the annular gasket itself, minute gaps inevitably exist at the contact surfaces between the battery case and the gasket, and between the sealing plate and the gas grip. The electrolyte leaks out of the battery through the gap, and moisture in the air enters the battery through the gap and reacts with the light metal negative electrode such as lyticum or sodium, causing an increase in the internal resistance of the battery. There is a problem.

In view of such circumstances, the inventors of the present invention interposed sealants between the gas gut and the battery case and between the gasket and the sealing plate to improve leakage resistance and to increase internal resistance during storage. As a result of various efforts to suppress this phenomenon, we have found that when a vinyl acetate homopolymer or copolymer is added to straight asphalt and used as a sealant, it has good leakage resistance and increases internal resistance during storage. discovered that an organic electrolyte battery with less
K completed the present invention.

In the present invention, a homopolymer or copolymer of vinyl acetate is added to straight asphalt as described above, and examples of the copolymer of vinyl acetate include, for example, a copolymer of vinyl acetate and ethylene; Copolymers of vinyl acetate and acrylic esters, copolymers of vinyl acetate and vinyl chloride, copolymers of vinyl acetate and vinyl ether, copolymers of vinyl acetate and vinyl esters, etc. are used. The amount of vinyl acetate homopolymer or copolymer added to straight asphalt is 0.
A range of 2 to 6.04 (heavy fIL ratio, hereinafter the same) is preferable. This is because if the amount of the vinyl acetate homopolymer or copolymer added is less than 0.2%, the adhesion between the sealant and the annular gasket will be poor, and if it exceeds 6%, the sealant will react with the electrolyte. This is because there is a risk that the battery characteristics will deteriorate.

When the sealant is used, it is dissolved in an organic solvent such as toluene or xylene, and applied as a solution to a desired position such as an annular gasket, a battery case, or a sealing plate. After the members coated with the sealant are dried to remove the organic solvent, they are used for battery assembly.

The above sealant has good resistance to electrolytes,
Therefore, the organic solvent used in the electrolyte is not particularly limited. Therefore, as the electrolyte, all those commonly used in this type of battery can be used, such as propylene carbonate, r-butyrolactone, tetrahydrofuran,
．． Preferably used is a solvent such as 2-dimethoxyethane or dioxolane, or a mixed solvent of two or more thereof, in which an electrolyte such as chloric acid chloride or chlorinated chloride is dissolved.

In the battery of the present invention, as the negative electrode active material, for example, lithium, sodium, magnesium, aluminum, etc. are used, and as the positive electrode active material, for example, manganese dioxide, carbon fluoride, iron sulfide, oxidized steel, etc. are used alone or in combination. A mixture of the above is used.

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a partial sectional view showing an embodiment of the organic electrolyte battery of the present invention, and FIG. 2 is an enlarged view of the main parts thereof.

The illustrated battery of the present invention is made of propylene carbonate 1.8-
A button-shaped battery with dimensions of 11.5 m in diameter and 8.06 am in height is used, using an electrolyte in which 0.5 mol/l of chloric acid is dissolved in a mixed solvent with a volume ratio of 1:1 with dioxolane. It's a battery. In the drawing, (1) is a sealing plate made of a nickel-stainless steel clad plate that also serves as a negative electrode terminal, and a stainless steel mesh (2) is attached to the inner surface of this sealing plate (1).
are spot welded, and lithium is pressed onto the net portion (2) to form a negative electrode (3).

(4) is a positive electrode formed by molding a positive electrode mixture whose main components are positive electrode active materials such as manganese dioxide, carbon fluoride, iron sulfide, and copper oxide, and (6) is an annular pedestal made of stainless steel. , (6) is a separator made by stacking two microporous polypropylene films. (7) is a battery case which also serves as a positive terminal, and this battery case (7) is made of iron with nickel plating on the surface, stainless steel, nickel-stainless steel clad plate, etc.

(8) is an annular gas grip made of polypropylene, (9)
is a sealant made by adding a homopolymer or copolymer of straight astral) K vinyl acetate, and the annular gasket (8) is fitted into the circumferential folded portion of the sealing plate (1), and the sealant is attached to the battery case. By tightening the opening end of (7) inward, the sealant (9) is applied to the battery case (7).
) and a sealing plate (11K pressure bonded to create a sealed structure inside the battery.

Next, a battery A of the present invention was prepared using a mixture of iron disulfide and cupric oxide in a weight ratio of 1:1 as a positive electrode active material, and a sealant was applied to the annular gasket to obtain the above-described structure. The number of leaking batteries and the change in internal resistance of the batteries were investigated when batteries B and B without any sealant were stored for a specified period of time under high temperature and high humidity conditions of 60°C and relative humidity of 9 (l), and the results were calculated respectively. It is shown in Table 1 and Figure 8.

In the battery A of the present invention, the sealant is applied to the annular gasket using sealant 6, which is made by adding 1% of a copolymer of vinyl acetate and ethylene to straight asphalt.
The annular gasket was immersed in a solution of 96 parts of toluene dissolved in 96 parts of toluene, and after coating, it was vacuum dried at 60° C. for 2 hours.

Table 1 Next, manganese dioxide was used as the positive electrode active material, propylene carbonate was used as the electrolyte, and 1! -Battery C of the present invention coated with a sealant using 0.5 mol/l of lithium perchlorate dissolved in a mixed solvent with a volume ratio of 2:l with 1,2-dimethoxyethane and the sealant Conventional battery cell without coating was stored for a specified period under high temperature and high humidity conditions of 60°C and relative humidity of 9 liters.The number of leaking batteries and internal resistance change were investigated, and the number of leaking batteries was calculated as follows. Table 2 shows the internal resistance change of the battery, and FIG. 4 shows the internal resistance change of the battery.

Note that both batteries C and D have atactic polypropylene at the open end of the battery case.

Forms a resin film. Therefore, in Battery C of the present invention, the contact surface between the battery case and the annular gasket is left as is, and the copolymer of vinyl acetate and ethylene is applied to the straight asphalt only on the contact surface between the sealing plate and the annular gasket. When a sealing agent containing 1% m was applied to the folded edge of the sealing plate, it was interposed by K, and in battery case D, no sealing agent was used at all on the contact surface between the sealing plate and the annular gasket. .

In Table 2, the examples show cases in which the sealant is interposed between the annular gasket and the battery case and both at the opening between the annular gasket and the sealing plate, and cases in which the sealant is interposed between the annular gasket and the sealing plate. In this example, an active polypropylene film is interposed between the battery case and the annular gasket, but this is not the only example. Another material having a sealing effect, such as an active polypropylene film, may be interposed between the annular gasket and the annular gasket.

In addition, in the example, when the sealant is interposed both between the annular gasket and the battery case and between the annular gasket and the sealing plate, an example is shown in which the sealant is applied only to the annular gasket. You can apply a sealant to the contact surface with the annular gasket or the contact surface of the sealing plate with the annular gasket, or you can apply the sealant to these and then apply the sealant to the annular gasket. Good too. Furthermore, in the case where a sealant is interposed between the sealing plate and the annular gasket, an example in which the sealing plate pressure sealing agent is applied is shown, but the sealing agent may also be applied to the annular gasket side. A similar effect can be obtained by applying it to both the annular gasket and the sealing plate.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view showing an embodiment of the organic electrolyte battery of the present invention, and FIG. 2 is an enlarged view of the main parts thereof. FIG. 8 and FIG. 4 are diagrams showing changes in internal resistance during storage of the organic electrolyte battery of the present invention and the conventional organic electrolyte battery. (1)... Sealing plate, (3)... Negative electrode, (4)...
...Positive electrode, (7)...Battery case, (8)...Annular gasket, (9)...Sealant patent applicant Hitachi Maxell, Ltd.

Claims (1)

[Scope of Claims] 1. In an organic electrolyte battery comprising a light metal negative and positive electrode and an organic electrolyte electrolyte, a sealant made by adding a vinyl acetate homopolymer or copolymer to straight asphalt is used. An organic electrolyte battery characterized by: 2. The organic electrolyte battery according to claim 1, wherein the vinyl acetate homopolymer or copolymer is added in an amount of 0.2 to 5.0 weight/lqb in the sealant.