JPS62219463A - Positive electrode depolarizing mix for divalent silver oxide battery - Google Patents

Abstract

PURPOSE:To eliminate a difference in discharge voltage and suppress the self- decomposition of divalent silver oxide, by providing a silver layer on the whole surface of a formed body, and causing a titanium compound to be contained in the formed body, to constitute a positive electrode depolarizing mix for a divalent silver oxide battery. CONSTITUTION:A formed body 2 having divalent silver oxide as the main constituent of the body is treated with an aqueous solution containing titanium ions from a titanium trichloride or the like, which is a reducing agent, to contain a titanium compound inside. A silver layer 3 is then provided on the whole surface of the formed body 2 so that a pellet-like positive electrode depolarizing mix 1 is constituted. The mix 1 is then combined with a negative electrode of zinc or the like, a separator and so forth to constitute a divalent silver oxide battery. The silver layer 3 prevents the discharge voltage of the battery from taking two levels. The titanium compound suppresses the self- decomposition of the divalent silver oxide. Gas generation, two-level discharge, liquid leak and so forth are thus effectively prevented without adversely affecting the performance of the battery.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a positive electrode mixture for a silver divalent oxide battery, and more specifically, when incorporated into a silver divalent oxide battery, it eliminates the difference in discharge voltage, Moreover, the present invention relates to a stable positive electrode mixture in which self-decomposition of silver divalent oxide particles is suppressed.

[Conventional technology]

Silver oxide batteries that use silver oxide (AgO-Ag, o 2 ) as a positive electrode active material have traditionally been used as power sources for wristwatches, for example, because of their stable operating voltage.

Among them, divalent silver oxide CAg0) is monovalent silver oxide (Agt
Ago
Divalent silver oxide batteries are being considered that use silver divalent oxide as the positive electrode active material.

[Problem that the invention seeks to solve]

However, in putting into practical use a silver divalent oxide battery using AgO as a positive electrode active material, there are the following two problems. One of them is Ag during discharge.

→ Goo → Ag goes through the reduction process, so the terminal voltage goes through a two-stage discharge process, with an initial discharge potential of 1.8 V and a mid-term discharge potential of 1.55 V. . The second problem is that Ago is unstable in an alkaline solution, so it self-decomposes, reducing its electrical capacity, and the oxygen gas generated during self-decomposition increases the internal pressure of the battery, causing leakage and rupture of the battery. There is a risk of causing

First, as a method to solve the first problem above, (a)
A method has been proposed in which a positive electrode mixture is prepared by adding λgtO particles to g0 particles, and (ii) a method in which the surface of Ag0 particles or AgO molded bodies is reduced with a reducing agent such as hydrazine or alcohol. However, in (a) above, a large amount of Ag2O is used to obtain one stage of discharge voltage.
However, only a slight increase in capacitance, which is the effect of using Ago, can be obtained. In addition, although an open-circuit voltage of around 1.6 V was temporarily obtained in (2), it rose to 1.8 V during battery storage, and further caused self-decomposition of Ago in the alkaline electrolyte. The problem arose that it could not be suppressed.

On the other hand, as a means to solve the second problem, there is a method of providing a layer containing a stabilizer such as cadmium or tellurium on the inner wall of the positive electrode container (Japanese Unexamined Patent Publication No. 124852/1982), or a method of providing a layer containing a stabilizer such as cadmium or tellurium on the inner wall of the positive electrode container, or A method of treating an Ago molded body with a reducing agent containing a stabilizer such as cadmium or tellurium (Japanese Unexamined Patent Publication No. 58-947)
Publication No. 57), etc. have been proposed. However, as mentioned above, many of the reducing agents that have been proposed in the past are dangerous or toxic by themselves, and if they remain in a molded product such as a positive electrode mixture, they can cause problems such as deterioration of battery capacity. This had a strong possibility of adversely affecting performance and was not suitable for practical use.

The present invention solves these conventional problems and is a stable silver divalent oxide battery that can achieve a single discharge voltage without any step when incorporated into a battery, and in which self-decomposition of A20 particles is suppressed. The purpose of this project is to obtain a positive electrode mixture for use without using harmful substances that adversely affect battery performance.

[Means for solving problems]

As a result of intensive research to achieve the above object, the present inventors formed a positive electrode mixture containing Ago as the main active material into, for example, a pellet shape, and then formed the formed body into a titanium ion (1)T
When treated with an aqueous solution containing iN, the surface of the molded body is reduced as shown in the following formula (1), and titanium ions are oxidized to form titanium compounds such as titanium oxide (Tie, ). I paid attention. By containing this titanium compound inside the molded body, it suppresses self-decomposition of AgO and acts as a stabilizer. In other words, it was confirmed that titanium ions (1) act as a reducing agent for the positive electrode mixture, and at the same time as they are reduced, titanium compounds such as Tie, which are produced by oxidation, have the effect of stabilizing agents. , we have completed the present invention.

That is, the positive electrode mixture for divalent silver oxide batteries of the present invention is a molded product mainly composed of divalent silver oxide, in which a silver (Ag) layer is formed on the entire surface of the molded product, and It is characterized by containing a titanium compound inside its body, and its manufacturing method involves treating a molded body made of powder containing silver divalent oxide as a main component with an alkaline aqueous solution containing titanium ions (1). It is a feature.

[Effect]

The positive electrode mixture for silver divalent oxide batteries of the present invention is composed of a molded body whose main component is Ago, which is a positive electrode active material, and this molded body contains Ag, O, Ag, a binder, etc. in addition to AgO. You may do so. The shape and dimensions of the molded body are not limited in any way; for example, if it is to be used in a button-type battery, it may be in the form of a pellet as shown in FIG.

In FIG. 1, l is the positive electrode mixture of the present invention, which consists of an Ag0 layer 2 whose main component is silver divalent oxide containing a titanium compound, and an Ag layer 3 formed covering the entire surface of the Ag0 layer 2. configured.

The Ag layer 3, which is a coating layer, is a necessary component to further increase the discharge voltage during discharge, and must be formed on the entire surface of the pelletized positive electrode mixture. If even a part of the Ag0 layer 2 is exposed, the discharge voltage will become two stages as described above, which is not preferable. Note that this Ag layer 3
Since Ag is not an active material, if the layer thickness is too thick, the capacitance of the entire battery will decrease, so it is preferable to set the thickness appropriately in consideration of this.

Furthermore, in the positive electrode mixture of the present invention, a titanium compound is contained inside the Ag0 layer 2 whose main component is AgO. This titanium compound penetrates into the Ago layer 2 during the treatment process with titanium ions (1) of the positive electrode mixture, which will be described later. Although it is not clear yet, this titanium compound acts to suppress the self-decomposition of Ago, and as a result, it effectively prevents gas generation, double discharge, leakage, etc. in the obtained silver divalent oxide battery. can.

Next, an example of a method for producing the positive electrode mixture of the present invention will be explained.

As mentioned above, the present invention relates to A obtained by a conventional method.
A molded body containing gO as a main component is treated with an aqueous solution containing titanium ions (1) as a reducing agent. This aqueous solution containing titanium ions (1) is titanium trichloride TiCl
3. It can be easily prepared by dissolving a trivalent titanium compound such as titanium trifluoride Tip in water.

In such a reducing solution, the concentration of titanium ions (1) is not particularly limited, but if it is too dilute, it will not be able to exhibit sufficient reducing power, so it is usually set to 3 weight - 1 or more. It is preferable.

The step of treating the Ago molded body using this reducing solution is, for example, immersing the molded body in the reducing agent liquid, which is simple and advantageous from a process standpoint. In this immersion treatment process, if the temperature of the reducing solution is high, the reduction will proceed quickly and the processing time can be shortened, but on the other hand, if the temperature of the reducing solution is too high, the dissolved titanium compounds will Since some types decompose, it is preferable to set the temperature to about 30 to 60°C. Further, the processing time is preferably set appropriately depending on the concentration of the reducing solution, the solution temperature, or the thickness of the Ag layer 30 to be formed, but is usually about 10 minutes to 1 hour.

〔Example〕

(a) Manufacturing example of positive electrode mixture First, 100% by weight of Ag, 0 and 3 as a binder.
Ago containing % by weight of polytetrafluoroethylene
Pressure mold the powder to a diameter of 5.3am and a thickness of 0.58j.
A pellet-shaped molded body of II+ is manufactured. On the other hand, a 3% by weight titanium trichloride solution was prepared as a reducing agent solution, and the solution temperature was 40°C.
By immersing the above pellet-shaped molded body in the σ-reducing solution at °C for 30 minutes, AgO on the surface of the molded body was reduced to Ag, and a titanium compound was contained inside the molded body. Afterwards, this molded body is washed with water, dried, and then
Positive electrode mixture 1 for silver divalent oxide batteries of the present invention as shown in the figure
I got it. In addition, in this positive electrode mixture 1, the thickness of the Ag layer 3 on the surface was about 50 to 70 μm.

(b) Characteristic evaluation test of silver divalent oxide battery! A divalent silver oxide battery 11 having a button deaf structure as shown in FIG. 2 was manufactured using the positive electrode mixture 1 obtained in the above process. The outer diameter of this battery was 5.3zi+, and the height was 2.1mm. In FIG. 2, the positive electrode mixture 11 obtained above, that is, the molded body consisting of an Ag layer 3 on the entire surface and an internal K Ag0 layer 2, is housed in the bottom of the positive electrode container 12, and a separator 13 is placed on the top of the molded body. A negative electrode 14 made of zinc is filled.

Then, by sealing with a sealing plate 16 via a gasket 15 and bending the upper open end [7] of the positive electrode container 12 inward, the entire stain pond is sealed.

100 such silver divalent oxide batteries were each heated to a temperature of 60"
After being stored at C for 20 days, the open circuit voltage was measured and the number of gases generated inside the battery was investigated, and the results are shown in the table. In addition, the height of the gas generating battery is 9.
The battery was considered to have changed by 2 mm or more.

(c) Comparative Example 3 containing 10 parts (volume %) of methanol as the reducing agent liquid
A positive electrode mixture was produced in the same manner as in the above production example, except that an aqueous solution of 0% potassium hydroxide was used and the AgO molded body was immersed for 10 minutes at a temperature of 60 °C. The positive electrode mixture is similarly incorporated into a battery, and such battery 1
Each evaluation test was conducted on 00 pieces, and the results are also listed in the table.

Table [Effects of the Invention] As is clear from the above explanation, when the positive electrode mixture for divalent silver oxide batteries of the present invention is incorporated into a battery, the discharge voltage is the same as that of monovalent silver oxide. In addition, since self-decomposition of silver divalent oxide is suppressed, it is possible to provide a silver divalent oxide battery with almost no blisters caused by gas generation and a storage stability of μs, so its industrial value is extremely large.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view showing an example of the positive electrode mixture for divalent silver oxide batteries of the present invention, and FIG. 2 is a longitudinal sectional view of a divalent silver oxide battery using this positive electrode mixture.

Claims (1)

[Claims] In a positive electrode mixture for a silver divalent oxide battery consisting of a molded body containing silver divalent oxide (AgO) as a main component, a silver (Ag) layer is formed on the entire surface of the molded body, and the interior of the molded body is A positive electrode mixture for a silver divalent oxide battery, characterized in that a titanium compound is contained in the positive electrode mixture.