JPS60262350A - Flat type organic electrolyte battery - Google Patents

Abstract

PURPOSE:To prevent increase in internal resistance in the final stage of discharge without sacrifice of discharge capacity of a battery by specifying the volume of a current collector to the inner volume of the battery. CONSTITUTION:The volumn of a positive current collector 7 to the inner volumn of a battery is limited to 0.5-5%. When the volumn of current collector 7 is 0.5% or more, increase in internal resistance in the final stage of discharge can be prevented. When the volumn of current collector exceeds 5%, the volume of active material must be reduced. Therefore, discharge capacity is decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an improvement in an organic electrolyte battery using a light metal such as lithium as a negative electrode active material.

Structures of conventional examples and their problems In general, organic electrolyte batteries have high energy density, can be made smaller and lighter, and are less likely to leak, so they are used in small calculators, in place of other types of batteries. It is currently widely used as a power source for precision equipment such as electronic watches.

・To explain the configuration of this type of battery using the typical flat battery shown in Figure 1 as an example, 1 is a stainless steel battery case that also serves as a positive terminal, and 2 is a sealing plate that is also made of stainless steel and serves as a negative terminal. , 3 is lithium, which is a negative electrode active material, and is pressed onto the inner surface of the sealing plate 2. 4 is a molded positive electrode mixture consisting of a mixture of manganese dioxide, a conductive material and a binder; 5
6 is a polypropylene gasket, and 7 is a positive electrode current collector.

The electrolyte used is a mixture of propylene carbonate and 1,2-dimethoxyethane in which lithium perchlorate is dissolved.

In a flat battery having such a structure, in order to prevent the internal resistance of the battery from increasing until the end of discharge, the positive electrode current collector 7 is
is placed between the battery case 1 and the foot electrode mixture 4. Here, an explanation will be given by taking as an example a flat battery having a diameter of 16 ff and a height of 1.6 mm and having the structure shown in FIG. FIG. 2I shows the discharge curve of this cell.

A in the figure is a case where the positive electrode current collector 7 is not provided, and a large increase in internal resistance H is observed at the end of discharge. B in the diagram is the thickness o, lmm - side length 5F for this battery.
This is a discharge curve when a +lπ current collector is placed between the battery case and the positive electrode assembly. As is clear from this second tooth, the increase in internal resistance is suppressed to a small extent, and the effect of the current collector is recognized.

However, the problem here is the size of the positive electrode current collector. If the current collector is made too thick,
The volume occupied by the current collector relative to the battery internal volume increases,
The volume of the active material decreases, and the discharge capacity decreases. If you make it too small, you won't be able to expect the desired effect.

OBJECTS OF THE INVENTION An object of the present invention is to prevent an increase in internal resistance at the end of discharge in a flat organic electrolyte battery without reducing the battery discharge capacity even when a positive electrode current collector is used.

Structure of the Invention In order to achieve the above-mentioned object, the present invention improves battery internal volume! /(
On the other hand, the volume of the positive electrode current collector is 0.5 to 5%.

In this way, by defining the volume of the current collector relative to the internal volume of the battery, it is possible to prevent the internal resistance from increasing at the end of discharge without reducing the battery discharge capacity.

DESCRIPTION OF EMBODIMENTS The present invention will now be described using a flat organic electrolyte battery having a height of 1.6 cm and a diameter of 16 mm as shown in FIG. The components in this battery are the same as those described above.

Here, FIG. 3 shows the relationship between the volume of the positive electrode current collector in the internal volume of the battery and the internal resistance of this battery during 80 inch discharge. As is clear from the figure, the volume of the current collector is 0.5%JJ,
It can be seen that within the above range, it is possible to prevent the internal resistance from increasing at the end of discharge. Furthermore, Figure 4 shows the relationship between the volume occupied by the positive electrode current collector with respect to the internal volume of the battery and the discharge capacity of the battery.As is clear from the figure, when the volume occupied by the positive electrode current collector is 5% or more, , the volume of the battery active material must be reduced, resulting in a decrease in discharge capacity.

In this example, manganese dioxide was used as the positive electrode active material, but 7) oxides such as chlorinated graphite and copper oxide, and sulfides such as iron sulfide may also be used as the positive electrode active material. The same effect can be obtained.

Effects of the Invention As described above, the present invention provides a current collector that can prevent an increase in internal resistance at the end of discharge without reducing discharge capacity in a flat organic electrolyte battery. Yes, the effect is great.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a flat organic electrolyte battery, Figure 2 is a discharge curve diagram of the battery, and Figure 3 is a graph showing the ratio of the positive electrode current collector to the battery internal volume and the internal resistance at the end of discharge. Figure 4 is a diagram showing the relationship between the occupied volume ratio of the positive electrode current collector and the discharge capacity.
Middle positive electrode current collector G Person's name: Patent attorney Toshi Nakao (1 person) Figure 1 @ Figure 2 (%)

Claims (1)

[Claims] A flat type having a negative electrode made of a light metal such as lithium as an active material, which is crimped to the inner surface of a sealing plate, a positive electrode mixture, an organic electrolyte, and a positive electrode current collector placed between the positive electrode life agent and the battery case. A flat organic electrolyte battery in which the volume of the positive electrode current collector accounts for 0.5 to 5% of the internal volume of the battery.