JPS58152375A - Organic electrolyte battery - Google Patents

Abstract

PURPOSE:To prevent any increase in the internal resistance of an organic electrolyte battery which might be caused during preservation of the battery by suppressing the polymerization of a cyclic-ether-system organic solvent by performing alkali treatment on iron sulfide used as a positive active material so as to neutralize the acid group existing in the surface of said iron sulfide. CONSTITUTION:In an organic electrolyte battery, a negative electrode 7 is prepared by using a light metal such as lithium as a negative active material, a positive electrode 1 is prepared by using iron sulfide the acid group existing in the surface of which is neutralized by alkali treatment as a positive active material, and electrolyte is prepared by using a cyclic-ether-system organic solvent as a solvent. In addition, such an organic electrolyte battery is constituted by the combination of a separator 4, a positive can 3, a negative can 5 and a gasket 8. Therefore, since the alkali treatment is performed on the iron sulfide, any reduction of the electric conductivity of the battery which might be caused due to the polymerization of the cyclic-ether-system organic solvent caused by the acid group existing in the surface of the iron sulfide can be prevented. Consequently, the preservation performance of the battery can be improved by decreasing the increase in the internal resistance of the battery.

Description

Detailed Description of the Invention The present invention uses a light metal such as lithium as a negative electrode active material, iron sulfide as a type of positive electrode active material, and a cyclic ether-based organic solvent or a mixed solvent containing at least a cyclic ether-based organic solvent. The purpose of the present invention is to improve organic electrolyte batteries that use organic electrolyte as a solvent for electrolyte, and particularly to improve storage performance.

Organic electrolyte batteries that use iron sulfide as a positive electrode active material have a larger electrical capacity per unit volume and a discharge voltage of approximately 1. 5. It has the characteristic of being compatible with commercially available Lecrancier batteries and silver oxide batteries, and its development as a high energy density battery with a large electrical capacity is expected.

And - in this type of pond, cyclic ether organic solvents such as dioxolane, tetrahydrofuran, and propylene oxide are preferred as solvents for electrolytes because of their high solubility of solutes and high conductivity, and can be used alone or These cyclic ether organic solvents are mixed with other organic solvents and used as electrolyte solvents, but these cyclic ether-based organic solvents do not react with acids, and some of the C-0-C ether bonds in the heterocycle are reacted by the acid VC. Tends to cleave and polymerize.

By the way, the iron sulfide having the above-mentioned characteristics has an acidic group on its surface, and when it is used as a positive electrode active material of a battery using a cyclic ether-based organic solvent f as an electrolyte solvent, it becomes a cyclic ether-based organic solvent. The solvent becomes a polymer, the conductivity decreases, and the internal resistance increases during storage.

The present invention has been made to solve such problems, and by treating iron sulfide with an alkali to neutralize the surface acidic groups and then using it as a positive electrode active material, it is possible to use a cyclic ether-based organic solvent. The purpose is to suppress polymerization and prevent an increase in internal resistance during battery storage.

That is, the present invention provides a negative electrode in which a light metal such as lithium is used as a negative electrode active material, a positive electrode in which iron sulfide is used as a positive electrode active material, and a cyclic ether-based organic solvent or a mixed solvent containing at least a cyclic ether-based organic solvent. The present invention relates to an organic electrolyte battery having an electrolytic solution using a solvent as a solvent, wherein the iron sulfide is treated with an alkali.

Examples of light metals used as negative electrode active materials in the present invention include lithium, sodium, magnesium, and aluminum, and examples of iron sulfides include ferrous sulfide (Fed) and ferric sulfide (Fe2S3"). Ferrous disulfide (pest) and the like can also be used in the same way as FeS, which is represented by the general formula FexS and is generally commercially available as ferrous sulfide.

As the alkali for alkali treatment of iron sulfide, for example, lithium hydroxide, sodium hydroxide, potassium hydroxide, etc. are used, and lithium hydroxide is particularly preferred. The alkali treatment is carried out, for example, by dissolving the alkali in water and immersing the powdered iron sulfide in the bath solution. The concentration of alkali is preferably about 2 to 10% by weight, and heating and stirring may be used during the casing treatment.

In the present invention, iron sulfide is used as a type of positive electrode active material, and iron sulfide alone is used as a positive electrode active material, and iron sulfide is used in combination with other positive electrode active materials such as copper oxide. This refers to the case where it is used as a positive electrode active material. As the copper oxide, cuprous oxide, cupric oxide, etc. are used, and when used together with iron sulfide, the ratio of iron sulfide and copper oxide is 75:25-25: 7
The range of 5 is preferably 0. As the cyclic ether organic solvent, for example, dioxolane, tetrahydrofuran, propylene oxide, etc. are used, and these may be used alone or in combination with each other, or propylene carbonate, γ-butyrolactone, l, 2- It is used in combination with other organic solvents such as dimethoxyethane. The electrolytic solution is prepared by dissolving an electrolyte such as lithium perchlorate or lithium boro7tride in these cyclic ether organic solvents or a mixed solvent of these cyclic ether organic solvents and other organic solvents. .

Next, the present invention will be explained with reference to Examples.

Iron disulfide (FeS2) powder was treated with a large excess of lithium hydroxide in a water retention solution for 1 hour while stirring, and then filtered and washed with water. After washing with water, it was vacuum dried at 100°C for 4 hours. The disappearance of the acidic groups on the surface of iron disulfide can be achieved by dispersing iron disulfide in water, and using a methyl red indicator, the dispersion does not turn acidic red, but instead takes on a basic yellow color. confirmed by.

Next, iron disulfide treated with alkali as described above was mixed with ferric oxide (Cu 2 O), acetylene black, polytetrafluoroethylene, etc. to prepare a mixture.

The mixture composition is 40 parts iron disulfide (parts by weight, the same applies below)
, 40 parts of cupric oxide, 15 parts of acetylene black, and 2 parts of polytetrafluoroethylene. This mixture is filled into a mold equipped with a stainless steel annular pedestal, and Q
, 5 t/as2, and this was used as a positive electrode.

The above positive electrode, a negative electrode made of a lithium plate with a diameter of 6.8 al and a thickness of La1ty, propylene carbonate and 1.8 al.
- Using an electrolytic solution in which 1 mol/l of lithium perchlorate was dissolved in a mixed solvent with a volume ratio of 1:1 with dioxolane, the first
The configuration shown in the figure has a diameter of 9.5ff and a height of 8.6fl.
An organic electrolyte battery was assembled using a conventional method. In FIG. 1, (1) is the above-mentioned positive electrode, (2) is the above-mentioned annular pedestal, and (3) is an iron positive electrode can whose outer surface is nickel-plated. (4) is a separator made of polypropylene nonwoven fabric, (5) is a negative electrode can made of a nickel-stainless steel clad plate, and a stainless steel mesh (6) is spot-welded to the inner surface of this negative electrode can (5). The net (6
) The negative electrode (7) is crimped onto the portion. and(
8) is an annular gasket made of polypropylene.

FIG. 2 shows the change in internal resistance of Battery A having the above structure and Battery B, which was made using iron disulfide without alkali treatment, and was stored at 60° C. for a predetermined period of time.

Battery B is an organic electrolyte battery having the same structure as Battery A, except that the iron disulfide is not treated with alkali, and the internal resistance measurements were all conducted at 20°C.

As shown in FIG. 2, the battery A of the present invention shows less increase in internal resistance due to storage than the conventional battery B.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an embodiment of the organic electrolyte battery of the present invention, and FIG. 2 is a diagram showing internal resistance changes during storage of the organic electrolyte battery of the present invention and a conventional organic electrolyte battery. be. (1)...Positive electrode, (7)...Negative electrode Figure 1 Figure 2 0 20 40 60 80 Storage period CB)

Claims (1)

[Claims] 1. A negative electrode using a light metal such as lithium as a negative electrode active material,
An organic electrolyte battery having a positive electrode having iron sulfide as one type of positive electrode active material, and an electrolyte having a cyclic ether-based organic solvent or a mixed solvent containing at least a cyclic ether-based organic solvent as a solvent, An organic electrolyte battery characterized in that sulfide is treated with an alkali.