JPS5821782B2 - battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a battery using a light metal such as lithium or magnesium as a negative electrode active material and an organic electrolyte.

In this type of battery, fluorocarbon,
Cupric oxide and the like are known, but according to the discharge reaction formula, the volume of the production system should be smaller than that of the raw yarn.

However, in actual batteries, the positive electrode greatly expands and absorbs electrolyte, which tends to cause a shortage of liquid near the negative electrode, which increases the polarization of the negative electrode and interferes with normal discharge.

In particular, in batteries that use fluorocarbon as the positive electrode active material, fluorocarbon is an intercalation compound obtained by directly reacting fluorine gas with raw material carbon at high temperatures, and X-ray analysis shows that it is not a raw material. Fluorine penetrates between the carbon layers and bonds with the carbon, causing the interlayers to widen.

Furthermore, it is known that in the discharge reaction, negative electrode light metal ions, such as lithium ions, enter between the layers and combine with fluorine.

Fluorocarbon reacts to form carbon and lithium fluoride, and the latter remains between the layers, making it difficult for the interlayer distance to become small.

The starting material, fluorocarbon, has a small surface energy.
Although it is essentially liquid repellent to the electrolyte, its liquid repellency decreases with discharge for the reasons stated above, and the electrolyte enters between the layers and is trapped in the positive electrode, expanding as an electrode.

In order to eliminate this drawback, lithium fluoride is dissolved and separated from the interlayers, and after the lithium fluoride is eluted, the distance between the carbon layers is reduced to the distance of the van der Waals radius.

When this happens, the amount of electrolyte stored decreases, and the product lithium fluoride dissolves into the electrolyte, so the battery no longer has a shortage of electrolyte, and no products are deposited on the surface of the positive electrode. Therefore, the decrease in discharge current density is small and there is no expansion of the positive electrode, which is advantageous for high rate discharge and flat type batteries.

However, until now, no solvent has been found that can dissolve fluorides such as lithium fluoride, which are discharge products, and that can be stably mixed with organic solvents.

As a result of various studies on additives that satisfy the above conditions, the present inventors found that macroheterobicyclic diamine [211 ] was found to be effective.

This macroheterobicyclic diamine (211) takes in lithium fluoride more strongly than crown ether and suppresses the expansion of the positive electrode after discharge.

The polarization of the negative electrode is also kept small.

This effect is remarkable in flat batteries.

This flat type battery has strict standards for the total height of the battery, and if it swells after discharge, it is necessary to reduce the filling capacity in order to take this into account.

Furthermore, since the total height is small, it is difficult to inject liquid into the battery, and the discharge utilization rate is low due to the polarization of the negative electrode when it swells as described above.However, adding cryptate as described above This made it possible to eliminate all of these drawbacks.

Hereinafter, the present invention will be explained with reference to examples thereof.

FIG. 11 shows a fluorocarbon-lithium flat type battery, where 1 is a case made of a stainless steel plate with a thickness of 0.3011 mm, and 2 is a sealing plate made of the same material.

3 is a 0.1 mm thick nickel lath plate welded to the inner surface of the sealing plate 2, and on top of this is a 0.3511 mm thick nickel lath plate welded to the inner surface of the sealing plate 2. - The negative electrode 4 is constructed by press-bonding a lithium sheet with a diameter of 18 squares.

5 is a positive electrode with a diameter of 17 mm and a thickness of 1.1 mm, and is made of fluorocarbon 1.
A mixture of 0.00 parts by weight, 11 parts by weight of acetylene black, and 20 parts by weight of a fluororesin binder was compression molded in a case 1 to which a titanium lath plate 6 was welded.

7 is a polypropylene liquid retaining material, 8 is a polypropylene separator, and 9 is a gasket.

The electrolyte contains 1 mol/ml of a solvent containing propylene carbonate and 1,2-dimethoxyethane mixed in a volume ratio of 1:1.
0.15 cc of a solution containing up to about 9 parts by weight of macroheterobicyclic diamine 211 was poured into the battery and sealed.

This battery has an outer diameter of 22.9ml! L, total height 2.45 mm
The capacity is 150 mAh.

With the above configuration, the content of microheterobicyclic diamine (211) in the electrolyte is 0%, 2.9% by weight, and 4% by weight.
．． 7% by weight and 9.1% by weight respectively a + b
Figure 2 shows the characteristics when discharging with a resistance of IKΩ as a load at 20°C with +cl d.

The following table shows the discharge capacity, utilization rate, and total height of the battery when the battery was discharged under the same conditions until the terminal voltage reached 2V.

Next, the electrolyte macroheterobicyclic diamine [
The relationship between the content of 211] and the discharge capacity is shown in FIG.

From the above results, it can be seen that by adding macroheterobicyclic diamine (211) to the electrolyte, the battery characteristics are improved and the change in the total battery height is also extremely small.

In the case of the above example, the maximum allowable total height of the battery is 2.55 m.
m, the utilization rate is 90% in high rate discharge as above.
However, judging from the change in the total battery height after discharge,
It is possible to further increase the discharge capacity by increasing the amount of active material filled.

From FIG. 3, the content of the additive in the electrolyte is particularly from 3 to 7.
A weight percent range is preferred.

Although fluorinated carbon was used as the positive electrode active material in the above example, even when using a fluorine compound that produces negative electrode light metal fluoride during discharge, it is effective in improving the discharge characteristics by eluting and removing discharge products from the positive electrode. be.

Brief Description of the Drawings Figure 1 is a longitudinal cross-sectional view of a fluorocarbon-lithium battery according to an embodiment of the present invention, and Figure 2 is a longitudinal cross-sectional view of a fluorocarbon-lithium battery according to an embodiment of the present invention. FIG. 3, a diagram comparing the discharge characteristics of batteries, shows the relationship between the content of macroheterobicyclic diamine (211) in the electrolyte and the discharge capacity.

4...Negative electrode, 5-...Positive electrode, 7...
...Liquid retaining material, 8...Separator.

Claims (1)

[Scope of Claims] 1. A battery comprising a negative electrode containing a light metal as an active material, a positive electrode, and an organic electrolyte, the battery comprising a macroheterobicyclic diamine (211) added to the electrolyte. 2 Macroheterobicyclic diamine in electrolyte (2
11. The battery according to claim 1, wherein the content of 11) is 3 to 7% by weight.