JPS61227365A - Organic electrolyte battery - Google Patents

Abstract

PURPOSE:To minimize the initial open circuit voltage by using a liquid organic electrolyte containing iodine and to enable the open circuit voltage of the battery to be set to a desired level by controlling the content of the alkali metal iodide. CONSTITUTION:After a nonwoven polypropylene fabric used as a separator is placed on a negative lithium electrode, a plastic gasket is attached to the separator. Next, a liquid organic electrolyte containing iodine is poured onto the separator and than a manganese dioxide pellet is placed on the separator. After that, the thus formed body is sealed in a positive and a negative can be caulking, thereby assembling a flat organic electrolyte battery with a diameter of 20mm and a thickness of 2.45mm. The liquid organic electrolyte is prepared by dissolving a 2X10<-1>mol/l concentration of iodine in a 1mol/l propylene carbonate solution of lithium perchlorate. The open circuit voltage of this battery is 3.18V immediately after its assembly and increases to 3.28V after one- week storage in an atmosphere maintained at 30 deg.C. But, it does not increase to a level over 0.38V even when the battery is stored for over one month.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a so-called organic electrolyte battery in which lithium is used as the active material of the cathode, manganese dioxide is used as the active material of the anode, and an organic solvent is used as the electrolyte. Specifically, the present invention relates to improving the open circuit voltage of the organic electrolyte battery.

[Conventional technology]

An organic electrolyte battery that uses metallic lithium, which has a high electronegativity, as the negative electrode active material and manganese dioxide as the anode active material exhibits a high battery voltage of approximately 3 cm because the electrode potential of the metallic lithium is extremely low (existing The battery is about 1.5V
), and because the electric capacity per unit weight of the metal lithium is large, it is known as one of the batteries with high energy density. In this type of battery, the electrolyte used is an electrolyte such as lithium perchlorate dissolved in an organic solvent such as propylene carbonate, and both metallic lithium and manganese dioxide are extremely stable in this electrolyte. The battery capacity does not decrease even when stored for a long period of time, and it has excellent storage stability.

Therefore, in recent years, organic electrolyte batteries have been increasingly used as backup power sources for electronic watches and IC memories that require long-term reliability.

By the way, it is known that in the organic electrolyte battery, the initial open circuit voltage is as high as 3.5 to 3.6 V, and the voltage decreases to about 3.0 V within a short time after use. This is due to a small amount of high potential part contained in manganese dioxide, which is the active material of the anode. When actually used, this high potential part immediately discharges, and then becomes the original voltage of the organic electrolyte battery.

Therefore, the above organic electrolyte battery can be used in electronic watches and ICs.
When used in electronic equipment that requires precision, such as a memory backup power supply, the initial open circuit voltage of this battery is high, which may cause these electronic equipment to malfunction, go awry, or even stop working. , there is a problem with credibility. Therefore, it is necessary to suppress the open circuit voltage of the organic electrolyte battery to at least 3.3V or less.

Therefore, conventionally, in order to eliminate the high potential of the open circuit voltage of the organic electrolyte battery, after manufacturing the battery,
The initial open-circuit voltage of 3.5V or higher was lowered to about 3.2V by pre-discharging with a current of 20mA/cm2.

[Problem that the invention seeks to solve]

However, the preliminary discharge is not effective if the discharge time is short, and it is necessary to discharge about 2 to 5% of the battery capacity, which requires a discharge time of about 5 to 10 minutes. Therefore, in the manufacturing process, this pre-discharge is an impediment to mass production, and the loss of battery capacity due to the pre-discharge is also a major drawback.

SUMMARY OF THE INVENTION The present invention has been proposed in order to solve the above-mentioned drawbacks, and it is an object of the present invention to provide an organic electrolyte battery that has a desired initial open circuit voltage and a large battery capacity even without the above-mentioned preliminary discharge. With the goal.

[Means for solving problems]

The inventor of the present invention has conducted intensive research over a long period of time to improve the initial open circuit voltage of organic electrolyte batteries, and has found that by incorporating iodine into the organic electrolyte, the initial open circuit voltage of the organic electrolyte batteries can be suppressed. , Furthermore, by adjusting the content of iodine, the open circuit voltage can be adjusted within a predetermined range (3,0
~3.3V).

The organic electrolyte battery of the present invention was completed based on such knowledge, and consists of a cathode mainly composed of lithium, an anode mainly composed of manganese dioxide, and an organic electrolyte, and the organic electrolyte is composed of an iodine-based anode. It is characterized by containing.

As shown in FIG. 1, the organic electrolyte battery of the present invention uses metallic lithium (1) as a cathode active material, manganese dioxide pellets (2) made of electrolytic manganese dioxide, etc. as an anode active material, and each of these Active material (1), (2
) is filled into the cathode can (4) and the anode can (5) through the separator (3) impregnated with an organic electrolyte, and further,
Gasket (6), (
6) are fitted together.

Here, as the organic electrolyte, propylene carbonate, butyrolactone, tetrahydrofuran, 1.2-
Further, iodine (■2) is added to an electrolytic solution in which an electrolyte such as lithium perchlorate or lithium borofluoride is dissolved in an organic solvent such as dimethoxyethane or 1,3-dioxolane alone or in a mixture of two or more. Use the added one.

Moreover, the content of this iodine is preferably in the range of 1.5X10-' to 1°Qx 104 mol/J. This content is 1.5X 10'2 mol/j! Below, the open circuit voltage cannot be suppressed to 3.3V or less, and the content is 1.
．． 0×10°'+aol/j! In the above, when the organic electrolyte battery is left at an extremely low temperature (about -20°C),
This is undesirable because the solubility of iodine in the organic electrolyte decreases and iodine precipitates inside the battery, making it impossible to provide a battery with stable battery voltage.

[Effect]

Therefore, in the organic electrolyte battery of the present invention, since the organic electrolyte contains iodine, the initial open circuit voltage of the organic electrolyte battery can be suppressed without pre-discharging.

〔Example〕

Hereinafter, specific examples of the present invention will be described.

Example 1 9.3 parts by weight of graphite was added to 88.9 parts by weight of commercially available electrolytic manganese dioxide heat-treated at 300°C for about 5 hours, and 1.8 parts by weight of polytetrafluoroethylene was added as a binder. This anode mix has a diameter of 15.5 mm+ and a weight of 0.655 g.
A manganese dioxide pellet was produced by molding it into a pellet shape.

On the other hand, a lithium foil with a thickness of 0.4On+m was
A lithium cathode was produced by punching out a lithium cathode, pressing it against a cathode can, and pasting it together.

Then, a separator was placed on the lithium cathode.

After placing a polypropylene non-woven fabric in the holder and fitting a plastic gasket, an iodine-containing organic electrolyte was injected, the manganese dioxide pellets were put in, the anode can was covered, and the container was sealed by caulking, as shown in Figure 1. A flat organic electrolyte battery with a diameter of 20 mm+ and a thickness of 2°45 vs. as shown was fabricated.

Here, the organic electrolyte is a solution in which lithium perchlorate is dissolved in propylene carbonate at a concentration of 1 mol/l, and iodine is further added at a concentration of 2 x 10' mol/l. The dissolved solution was used.

Comparative Example 1 In Example 1 above, a solution of lithium perchlorate dissolved in propylene carbonate at a concentration of 1 mol/β was used as the organic electrolyte, as in the conventional case, and all other conditions were the same as in Example 1. An organic electrolyte battery was prepared in the same manner as described above.

Comparative Example 2 After producing an organic electrolyte battery in the same manner as in Comparative Example 1 above, this battery was pre-discharged to 3% of the battery capacity to produce an organic electrolyte battery.

For each of the above samples, the open circuit voltage was measured immediately after the battery was prepared, after being stored in a 60°C atmosphere for one week, and after being stored in a 60°C atmosphere for one month. The results are shown in Table 1.

(Margin below) Table 1 From Table 1, the sample of Comparative Example 1, which is the same as the conventional one, immediately after fabrication.
The one-way voltage after storage for one week and one month was 3.
In contrast, the sample of Example 1, in which the organic electrolyte contained iodine, showed a low open circuit voltage of 3.18 V immediately after preparation, and even when stored for a long period in an atmosphere at 60°C. It was confirmed that the open circuit voltage increased to 3.28V after one week of storage, but the open circuit voltage did not exceed 3.28V even after one month of storage. This is comparable to Comparative Example 2 in which preliminary discharge was performed, and can even be said to be superior.

That is, it has been found that by incorporating iodine into the organic electrolyte, it is possible to suppress the open circuit voltage to a low level (3.3 V or less) without the need for troublesome operations such as preliminary discharge.

Therefore, the present inventor conducted the following experiment in order to determine the appropriate content of iodine in the organic electrolyte.

Example 2 Organic electrolyte batteries were prepared in the same manner as in Example 1 except that the iodine content in the organic electrolyte was varied. The open circuit voltage was measured after storage for one week. The results are shown in Figure 1.

From Figure 1, the iodine content is 1.5X10'2m.

It can be seen that when the voltage is set to 1/J or more, the open circuit voltage can be suppressed to 3.3 V or less. However, the iodine content is 1
．． When the temperature increases to 0X10→II+0171 or higher, when the organic electrolyte battery is left at an extremely low temperature (approximately -20°C), the solubility of iodine in the organic electrolyte decreases,
Iodine will precipitate inside the battery, making the battery voltage unstable. Therefore, the practical content of iodine in the organic electrolyte is 1.5 x 10'2 to 1.5 x 10'2. OX 10'm
It is in the range of ol/l.

〔Effect of the invention〕

As is clear from the above explanation, in the organic electrolyte battery of the present invention, since the organic electrolyte contains iodine, the initial open circuit voltage can be lowered without performing preliminary discharge (
3.3 V or less), and by adjusting the iodine content, the open circuit voltage can be set to a desired voltage.

Therefore, a mine decomposition battery having a desired open-circuit voltage can be produced without the troublesome preliminary discharge as in the conventional method, so that the production time can be significantly shortened and mass production becomes possible. Furthermore, since there is no loss of battery capacity due to preliminary discharge, it is extremely advantageous in terms of battery capacity.

Therefore, the organic electrolyte battery of the present invention is suitable as a power source for precision instruments and the like that require long-term reliability.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of an example of an organic electrolyte battery according to the present invention, and Figure 2 is a characteristic diagram showing changes in open circuit voltage (after storage at 60°C for one week) with respect to iodine content in the organic electrolyte. be. 1...Metallic lithium 2...Manganese dioxide pellets 3...Organic electrolyte patent applicant Sony Everady Co., Ltd. agent Patent attorney Kobu Mima Sakae Enso

Claims (1)

[Claims] An organic electrolyte battery comprising a cathode mainly composed of lithium, an anode mainly composed of manganese dioxide, and an organic electrolyte, the organic electrolyte containing iodine.