JPS60131758A - Manufacture of nonaqueous electrolyte battery - Google Patents

Abstract

PURPOSE:To increase the discharge capacity of a nonaqueous electrolyte battery, which is constituted by using an alkali metal as the negative active material and nonaqueous electrolyte as the electrolyte, by subjecting a molded positive mixture to heat treatment performed in an atmosphere of a high concentration of oxygen. CONSTITUTION:After 100pts.wt. of manganese dioxide, 6pts.wt. of carbon and 5pts.wt. of a fluorine resin binder are mixed together, the mixture is molded into a disk-like pellet. The thus formed pellet is then put in an electric furnace the internal oxygen concentration of which is adjusted to 50-60% by feeding a given amount of oxygen from an oxygen bombe, and heated at 250 deg.C for 1hr before being cooled to make a positive mixture 4. Next, metallic lithium 2 is placed over the mixture 4 with a separator 3 interposed before nonaqueous electrolyte is poured, thereby constituting a coin-type battery. Therefore it is possible to increase the discharge capacity of the battery by heating the positive mixture 4 in an atmosphere of a high concentration of oxygen so as to cause oxygen to be absorbed by the mixture 4 in a short time and causing the oxygen absorbed to contribute to electric discharge reaction.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing a non-aqueous electrolyte battery.

Structures of conventional examples and their problems Typical non-aqueous electrolyte batteries that use alkali metals as negative electrode active materials include batteries that use lithium as the negative electrode active material and manganese dioxide or carbon fluoride as the positive electrode active material. be. These have been mainly used as coin-shaped lithium batteries in electronic devices such as electronic watches and calculators.

The conventional structure of this type of coin-type battery is to place a positive electrode mixture molded into a disk shape through a seven-layer plate inside a negative electrode sealing lid to which lithium is pressed, and an organic solvent and an inorganic electrolyte. A predetermined amount of a non-aqueous electrolyte was injected into the electrode, and a case that also served as a positive electrode terminal was placed over and sealed.

Batteries that use alkali metals such as lithium as negative electrode active materials have a strong reactivity with water, so
An organic solvent from which moisture has been removed is used as the electrolyte, and other battery components are also sufficiently dried.Battery assembly is also carried out in an air or inert gas atmosphere from which moisture has been removed. The drying ring for the positive electrode mixture molded in this device varies depending on the positive electrode active material used, but it is usually dried under reduced pressure or in the air at a temperature of 100 to 380°C. .

Batteries formed in this manner have been widely used in small electronic devices such as electronic watches, electronic calculators, and calculators. However, in recent years, the trend towards making these electronic devices smaller and lighter has progressed further, and there has been a demand for batteries used in these electronic devices to be smaller and have a larger electric capacity.

The easiest way to increase the electric capacity of a battery is to increase the amount of positive and negative active materials, but the size of the battery is limited and the battery contents within a certain volume are limited. There is a natural limit to the amount of content that can be increased, and considering the battery manufacturing conditions, increasing the amount of content unnecessarily will make battery assembly difficult and lead to a decrease in yield.
There was a problem that caused an increase in battery cost.

OBJECTS OF THE INVENTION The present invention provides a molded positive! By heating the mixture in an atmosphere with a high oxygen concentration, the electric capacity of the battery can be increased without increasing the filling amount of the battery contents, especially the positive electrode mixture. The purpose is to

Structure of the Invention The present invention involves molding a positive electrode mixture consisting of an active material, a conductive material, and a binder according to the battery size, and then heat-treating the mixture in a temperature atmosphere to adsorb oxygen to the positive electrode mixture in a short period of time. ,
The discharge capacity is increased by contributing the absorbed oxygen to the discharge reaction.

Description of examples Hereinafter, the present invention will be explained in detail with reference to Examples.

As shown in Fig. 1, a dish-shaped separator 3 is placed on a sealing lid 1 to which metal lithium 2 is crimped, and after pouring an electrolyte consisting of propylene carbonate, dimethoxyethane, persalt, and lithium dioxide, a positive electrode mixture is prepared. Beret 4 to Lithium 2
to face. The mixture contains 100 parts of manganese dioxide and 6 parts of carbon by weight.

Immediately after mixing 5 parts of fluororesin binder,
After molding into a disc-shaped pellet with thickness o and esMllI,
This was placed in an electric furnace into which a certain amount of oxygen was introduced from an oxygen cylinder and the oxygen concentration inside was adjusted to 50 to 60%, heated at a temperature of 260° C. for 1 hour, and then cooled.

This mixture pellet 4 is housed in the dish-shaped separator 3 and faces the lithium 2 . After that, the case 5 is placed over the sealing lid 1, the end of the case 75 is curled inward, and the gasket 6 is tightened to seal the case.
A coin-shaped battery with a thickness of 1.6 mm was formed.

Oxygen concentration is 0% (reduced pressure), 20-26% (atmosphere) 30
~40%, 60-60%, 70-80%.

The heating temperature is 160°C and 200°C.

260° C., 30° C. *Heating time was 1 hour for all investigations.

Figure 2 shows the oxygen concentration of the present invention at 50-60% and 1 at 250°C.
Battery a using time heat treated mixture and conventional battery 2 under reduced pressure
The discharge curve at 20°C of a load resistance of 30Ω for a battery using a mixture heat-treated at 60°C for 1 hour is shown. The battery of the present invention has a long discharge duration, a high battery voltage, and a large discharge capacity.

30° at each oxygen concentration and heating temperature, and 20° at G load.
As shown in Figure 3, the discharge duration at C is longer when the oxygen concentration is 30% or more, and the influence of heating temperature is smaller than when the oxygen concentration is 0 to 20%. . When the oxygen concentration is 30% or more, the heating temperature is 200%
~300°C is suitable.

If the temperature exceeds 300° C., combustion of carbon, which is an electric material in the positive electrode mixture, may occur in a high oxygen concentration atmosphere, which is not preferable.

The mechanism by which the discharge capacity increases due to heat treatment in this high oxygen concentration atmosphere is not clear.

It is thought that by heating in an oxygen atmosphere, oxygen is adsorbed to the mixture, and that the adsorbed oxygen acts as a positive electrode active material during battery discharge. In other words, in addition to the normal reaction between the positive electrode active material and the negative electrode active material, there is a reaction between the adsorbed oxygen and the negative electrode active material, for example, 02+ 4Li → 2L12
It is considered that 0 reactions occur.

Oxygen adsorption to the mixture is in the atmosphere (oxygen concentration 20-26%)
This occurs even when heated with water, but if oxygen is supplied artificially,
By setting the concentration to 0% or more, oxygen adsorption becomes easier.
), the effect of heating temperature is small, and discharge capacity can be improved even at relatively low heating temperatures.

Although the heating time was set to 1 hour, a sufficient effect could be obtained by heating for 10 minutes or more in an atmosphere with an oxygen concentration of 30% or more.

Further, in the examples, a battery using manganese dioxide as a positive electrode active material was described, but similar effects were obtained in a battery using fluorinated graphite as a positive electrode active material.

Effects of the Invention As described above, the present invention is capable of increasing the discharge capacity of a battery by heat-treating the positive electrode mixture of a non-aqueous electrolyte battery in an atmosphere with a high oxygen concentration of 30% or more. .

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a flat non-aqueous electrolyte battery obtained according to an embodiment of the present invention, FIG. 2 is a diagram showing discharge curves of the battery of the present invention and a conventional battery, and FIG. FIG. 3 is a diagram showing the relationship between the oxygen concentration during heat treatment of the positive electrode mixture at various temperatures and the discharge duration when each battery is discharged. 1...Sealing lid, 2...Negative electrode lithium,
3...Separate lake, 4...Positive electrode mixture,
5...K-7,,6...Gasket. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2: Diagonal Gate (h) Figure 3: Shunyuxuan (Shunyuxuan)

Claims (1)

[Claims] A method of manufacturing a battery using an alkali metal as the negative electrode active material and a non-aqueous electrolyte as the electrolyte, the method comprising heating a molded positive electrode mixture in an atmosphere with an oxygen concentration of 30% or more. Method of manufacturing electrolyte batteries.