JPS58166633A - Positive electrode for organic solvent cell - Google Patents

Abstract

PURPOSE:To improve a discharge characteristic especially the flatness of discharge voltage of an organic solvent cell, by using an iron disulfide dust, that is, iron sulfate, as the active material to form at least a part of positive electrode surface. CONSTITUTION:A positive electrode is prepared by the method, in which a dust of FeS2 conventionally used as the active material is suspended to aqueous solution of iron sulfate and then dried to adhesively attach the iron sulfate partly to an FeS2 surface, or the method, in which heat treatment of the dust of FeS2 is performed in air or oxygen gas to partly dissolve the FeS2 surface and obtain the iron sulfate, or the like. In this way, an organic solvent cell, in which flatness of discharge voltage can be improved further with a long discharge duration time and an excellent discharge characteristic, can be obtained.

Description

[Detailed Description of the Invention] [Technical field to which the invention pertains] The present invention relates to a positive electrode for organic solvent batteries, and in particular to a positive electrode for improving the discharge characteristics of an organic solvent battery, particularly the flatness of the discharge voltage. Regarding active materials.

[Prior art and its problems]

As a negative electrode active material? Organic solvent batteries using light metals such as aluminum and sodium have a high energy density, can be used over a wide temperature range, are attractive and have excellent storage characteristics, and are used in calculators, hour hands, and memory. It is widely used as a backup power source.

The power generation element of this organic solvent battery consists of a negative bridge, an electrolyte, and a positive electrode. Generally, a light metal such as aluminum or 9um is used as the negative electrode, and as the electrolyte,
A solution is used in which an electrolyte such as lithium perchlorate or lithium fluoroborate is dissolved in an organic solvent such as propylene carbonate, γ-butyrolactone, or dimethoxyethane.

In this organic solvent battery, the positive electrode active material is
In the 3v system, manganese dioxide CBl&Io,), carbon fluoride ((CFx)a)t, and in the 1.5v system, vinyl oxide, X v x rBl, 01), copper oxide (Cub)
, iron sulfide (Fed), iron dioxide rPe8. ) etc. are known.

On the other hand, as 1.3V batteries, silver oxide batteries and alkaline manganese batteries are widely used in small devices. However, although silver oxide batteries have excellent discharge characteristics, they are expensive, and alkaline manganese batteries have a problem in that the flatness of the discharge voltage during continuous discharge is poor.

Therefore, it has high energy density and excellent discharge characteristics.
There is a strong desire to develop an inexpensive 1.5V organic solvent battery.

Now, among the 1.5-inch organic solvent batteries in which a positive electrode containing the above-mentioned positive electrode active material and a lithium negative electrode are combined, those in which the positive electrode active material is CuO and Fe8 have a discharge voltage of 1.2 to 1.5 cm.
4 V 1. Il Vyo I34'4'low, Bl, O
, No. 2 has a high discharge voltage, but has poor voltage flatness and is expensive. Compared to these, Fe8. is attracting attention because of its large theoretical discharge capacity.

However, Fe8. Practical solvent batteries using C as a positive electrode active material have the disadvantage that the discharge voltage is generally higher than 1.8 V, and as the discharge progresses, the discharge voltage changes in two stages, resulting in poor discharge flatness.

[Purpose of the invention]

This invention was made to solve the above-mentioned drawbacks.1. The purpose of the present invention is to provide a positive electrode for organic solvent batteries that has excellent discharge voltage flatness and a large capacity density.

[Summary of the invention]

The positive electrode of the present invention is characterized in that the active material is iron disulfide powder whose surface is at least partially made of iron sulfate.

The positive electrode active material according to the present invention is Fe8. Fe8. A method of attaching iron sulfate to a part of the surface; or Fe8. The powder of Fe8. It can be prepared by decomposing a part of the surface of iron sulfate into iron sulfate, but the latter method is preferred in terms of ease of preparation. In the latter method, the F used
e8. Fe8. The amount of iron sulfate (Fe8
．． These conditions cannot be uniquely determined because the area, thickness, etc. covered with iron sulfate on the powder surface vary. For example, when heat-treating Pea powder with an average particle size of 10 to 50μ in the air, the temperature should be slowly raised from room temperature to 230 to 350μ.
It is preferable to perform heat treatment at a temperature of 4 to 5 hours. In any case, the active material according to the present invention is Fe8.
It is necessary that a portion of the surface of the powder, preferably a majority portion, be covered with iron sulfate.

The positive electrode of the present invention is prepared by mixing the active material prepared as described above with a commonly used conductive material such as graphite or acetylene black, and a binder such as polytetrafluoroethylene or botethylene, and then mixing the active material into a predetermined shape (for example, It can be obtained by forming into pellets).

〔Effect of the invention〕

By using the positive electrode thus obtained, it is possible to provide a 1.5 V organic solvent battery with excellent discharge voltage flatness and large discharge capacity.

[Embodiments of the invention]

The present invention will be explained in more detail below with reference to the organic solvent battery having the structure shown in FIG.

EXAMPLE Commercially available Fed powder (average particle size) was heated to 300'C in air at a rate of 5°C per minute, and heat-treated for 5 hours while maintaining the temperature at 300°C. It was confirmed by Xi1 diffraction and ESC that iron sulfate was produced on the powder surface after treatment. Weigh out 90.6% of the obtained F-8° powder, 7.4% of graphite powder, and 2.0% of baking soda powder, and mix it with a mixer to a diameter of 15mm.
A positive electrode 1 was produced by molding to a diameter of φ and a thickness of 0.4 cm.

Next, as shown in FIG. 1, the positive electrode 1 obtained by the above method and the negative electrode 2 made of a metal lithium disk were mixed with propylene carbonate in which 1 molar concentration of lithium perchlorate was dissolved.
After making contact with each other through a separator 8 impregnated with a mixed electrolyte with dimethoxyethane and loading them into a stainless steel battery case 4, a negative electrode sealing plate 5, which also serves as a negative electrode terminal, is attached to the battery case 4 around the edge. The opening of the battery case 4 was bent inward and sealed to assemble an organic solvent battery with a diameter of 20 and a total height of 1.6. This was called the battery man.

For comparison, Fe8. without the above heat treatment was used. A battery B was produced in the same manner as in the example except that the battery B was used.

When the constant load discharge characteristics of these two batteries were measured at room temperature of 13Ω, the results shown in FIG. 2 were obtained. In the figure, numeral ``person'' represents the discharge curve of the battery of the example, and ``B'' represents the discharge curve of battery B.

As is clear from the figure, battery A using the original strain of the present invention has improved flatness of discharge voltage compared to battery B using F@8, which does not have iron sulfate on the surface of the active material. Furthermore, the discharge duration is long.

As described above, when the positive electrode of the present invention is used, a T, SVI refreshing solvent battery with excellent discharge characteristics can be produced, and its industrial value is greatly increased.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of an example of an organic solvent battery for explaining the present invention, and FIG. 2 is a curve showing continuous discharge characteristics of batteries A and B. DESCRIPTION OF SYMBOLS 1... Positive electrode, Meaning... Negative stock (lithium disc), 3... Separator (impregnated with organic electrolyte and held), 4... Battery case, 5... Negative sealing plate, 6... ··gasket. Agent Patent attorney Kensuke Chika (1 other person)

Claims (1)

[Claims] A positive electrode for an organic solvent battery characterized by using as an active material iron disulfide powder whose surface is at least partially iron sulfate.