JPS58131668A - Rechargeable silver oxide cell - Google Patents

Abstract

PURPOSE:To suppress generation of O2 gas from a positive electrode at overcharge, prevent oxidation of a separator and suppress self discharge. CONSTITUTION:In a silver oxide cell in which zinc powder is used for a negative electrode and Ag2O is used as a main compound for a positive electrode while pulverized graphite mixed as necessary and molded is used as a conductive material further a caustic alkali solution is used as an electrolyte, negative electrode electric capacity (Ah) and positive electrode electric capacity (Ah) are obtained respectively from 0.820 X metal zinc weight (gr) + 0.659 X zinc oxide weight (gr) and 0.231 X silver oxide weight (gr) + 0.497 X metal silver weight (gr) +0.378 X manganese dioxide weight (gr), and its balance of electric capacity is established in a range such that negative electrode electric capacity/positive electrode electric capacity becomes 0.60-0.90.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in rechargeable silver oxide batteries, and includes suppressing the generation of 0□ gas from the anode during overcharging and suppressing the generation of 0□ gas by the 02 gas. The purpose is to prevent oxidation and suppress self-discharge of the generator.

Rechargeable silver oxide batteries maintain the characteristics of conventional silver oxide batteries commonly used in electronic wristwatches, such as large electrical capacity, low self-discharge, and excellent voltage flatness, and are rechargeable, allowing them to be recharged by sunlight. It was developed as a power source for battery-equipped wristwatches, etc. Furthermore, as the use of solar cells expands into calculators and other applications, it is expected that more high-performance, compact, rechargeable silver oxide batteries will be developed.

Rechargeable silver oxide batteries usually use human G20 as the main ingredient, and Ag and M
The anode mixture is formed by mixing nO2 and fine graphite as a conductive material and compression molding the mixture. This anode mixture is generally pressed onto the bottom of an anode case made of nickel-plated iron, and after absorbing the electrolyte, an alkali-resistant separator, flayer, and impregnating material layer are provided thereon. On top of the cathode body, a cathode body made of zinc hydrate powder as the main ingredient, zinc oxide and a thickener uniformly dispersed, and an electrolyte absorbed, is used, and this cathode body is placed in a cathode current collector container that also serves as a seal. . The upper part of the anode case is then bent inward and compressed through a glass gasket to form a battery.

Rechargeable silver oxide batteries are required to have improved overcharge resistance and charge/discharge characteristics, especially under charging voltage control, in addition to the storage properties and leakage resistance required of regular silver oxide batteries. ing. Therefore, in conventional rechargeable silver oxide batteries, we considered the type and amount of graphite added to the anode, and used graphite with surface functional groups removed to increase the overvoltage of 02 gas generation during charging. This suppresses gas generation during overcharging and prevents the battery from swelling. Also,
By suppressing the generation of 02 gas from the anode, the oxidation reaction of the separator and impregnating material is reduced, and self-discharge and charge/discharge characteristics are improved. It cannot be said that the generation of O gas has been sufficiently suppressed, and improvements are needed in the swelling and charge/discharge characteristics of the battery.

The present invention was developed based on the results of studies on suppressing the generation of 02 gas from the anode during overcharging of rechargeable silver oxide batteries, and preventing oxidation of the separator due to the 0□ gas and suppressing self-discharge. 1L air volume balance is calculated as cathode capacitance/anode capacitance (hydration capacitance (Ah) = 0.82
0X metal zinc weight (gr) 10, 659X zinc oxide weight (gr), anode electric capacity (Ah) = 0.231X silver oxide weight (gr) + 0, 497 X metal silver electric switch (gr)
+0.378 X manganese dioxide weight i (gr)) is 0.
It is characterized by being assembled within a range of 60 to 0.90.

When a silver oxide battery is charged, the following reaction can occur inside the battery: O 2Ag + 208- →Ag2O+ H2O+ 2e
-(1) Ag O+ 20H-→2Ago + H2O
+ 2e-(2) 20I(--+ I(20+ IAO
2+ 2e-(3)ZnOfHzO+2e--+ Z
n + 20H-<4) 2HzO+2a--+ H2
+ 20H-(5)Ag20+H2→ 2Ag +H2
0(6) Zn +IAO□-+ ZnO (7) Among the 02 and H2 gases generated when overcharging, 0° gas is easily absorbed by the force A according to equation (7), and H2 gas is absorbed by the force A in equation (6). Because it reacts slowly, it tends to accumulate inside the battery.

Moreover, in conventional silver oxide batteries, it was important to pack as much electrical capacity into the same volume, so the above cathode/anode electrical capacity ratio was pushed closer to 1.00, and a ratio of 0.90 or more The battery is designed. Therefore, since the amount of anode, ie, Ag2O and Ag, is relatively small, formula (6)
As the reaction progresses, H2 gas tends to accumulate, and as the charging current increases, the reactions of equations (1) and (2) cannot keep up, so zero gas is generated by the reaction of equation (3). Figures 1 and 2 show 2 at 60℃ with 1.85V quasi-constant voltage.
This figure shows the swelling of the battery and the amount of gas accumulated in the battery after 40 hours of overcharging. The cause of battery swelling is due to the gases generated, but the number of gases generated depends on yin and yang, protection and energy.

Furthermore, the cathode-anode capacitance ratio has a large influence on charge-discharge reversibility. This is due to the oxidation of the 7-9 reactor due to the generation of 02 gas and the accompanying self-discharge. Figure 3 shows the reverse behavior at a 9' direct voltage of 1.85 V and a depth of discharge of 0.5 inches. As the charging/discharging current increases, self-discharge increases, and this is due to the influence of the cathode-anode capacitance ratio. It shows that it is larger.

In this way, it is preferable to suppress the cathode-anode capacitance ratio to 0.90 F or less in order to improve the charging and discharging characteristics of rechargeable silver oxide batteries, but if the cathode-anode capacitance ratio becomes small, the discharge capacity of batteries of the same size will decrease. Since it becomes smaller, 0.60
It is clear that the following is not preferable.

Hereinafter, specific embodiments of the present invention will be described with reference to FIG. 1-Mn0z O-4g 1 to 99g Ag2O
Furthermore, after mixing and homogenizing 0.6 g of phosphorous graphite, 8
50 mm was weighed and molded into a metal container (also serving as an ultimate current collector) with a diameter of 10.9+ m and a thickness of 1.6 mm under a pressure of 12 mm and 74 mm. 30 μL of 45% by weight caustic alkaline electrolyte is absorbed into this anode mixture. On top of this mixture 6, an impregnating material 4 consisting of an alkali-resistant monolayer 5 and an alkali-resistant fiber is placed, and on top of that, the necessary amount of zinc oxide is added to the lead powder, and the electrolyte is poured. A cathode 2 made of liquid and glue is installed, and a sealing plate 1 which also serves as a cathode terminal is placed. This sealing plate 1
An elastic gasket 3 made of synthetic resin is provided around the periphery of the metal container 7, and the upper part of the metal container 7 is sealed via the gasket 3. 8
is a yang-yin ring. The type is R44 type (11,6xφ
.

5, 4.1llb).

240℃ at 60℃ with 1.85V quasi-constant voltage of this battery.
The swelling of the battery after overcharging and the amount of gas accumulated in the battery are shown in Figures 1 and 2 with dots, respectively.

Furthermore, the reversibility at a charging voltage of 1.85 V and a depth of discharge of 0.5 inches is also shown in FIG. 3 with an asterisk.

As described above, according to the present invention, it is possible to suppress the generation of 0 gas from the anode during overcharging, and to suppress the generation of 0 gas by the 02 gas.
A rechargeable silver oxide battery is created that prevents oxidation of the inverter and suppresses self-discharge.

[Brief explanation of the drawing]

Figure 1 shows the relationship between the cathode and anode capacitance ratio and battery swelling, Figure 2 shows the relationship between the cathode and anode capacitance ratio and gas generation tank, and Figure 3 shows the number of minute charge/discharge cycles and capacity remaining rate. FIG. 4 is a half-cut cross-sectional view of a rechargeable silver oxide battery obtained by the present invention.
...is sket, 4...impregnating material, 5...ce/IP
Rator, 6... Anode mixture, 7... Metal container, 8...
anode ring. Fig. 1 0.5 06 0.7 0.8 0.9 1.0 mm
+ Onishi (Trap (Enden (1 Tame, o) Fig. 2 0.5 0.6 0.7 08 0.9 10 Chin S Gokugai (g - (Emperor (River -68,) 3rd Figure Q12345 Light value, (I4 full autumn Figure 4

Claims (1)

[Claims] The negative electrode is made of zinc powder, the positive electrode is made of Ag2O as the main ingredient, and a necessary amount of finely powdered graphite is mixed as a conductive substance and then molded.
In a silver oxide battery using a caustic alkaline solution as the electrolyte, the cathode capacitance (Ah) is 0.820 x metal zinc weight (gr) + 0.659 zinc chloride weight (gr), and the anode capacitance (Ah) is 0.231 x Silver oxide weight (gr) + 0.497 x Metallic silver weight (gr) 10, 378 x Manganese dioxide weight (
A rechargeable silver oxide battery, characterized in that the capacitance balance is determined in the range of cathode capacitance/anode capacitance of 0.60 to 0.90.