JPH09320589A - Silver oxide battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silver oxide battery having an excellent electric characteristic and a large capacity. SOLUTION: In a silver oxide battery in which a zinc-containing negative electrode mix 2 enclosed in a negative electrode cup 6 and a positive electrode mix 1 enclosed in a positive electrode can 3 are stacked with a separator 4 between them, silver oxide powders with an average particle size of not less than 10μm and not more than 5μm and with a bulk density of not less than 1.2g/cm<3> and not more than 1.7g/cm<3> are used in the positive electrode mix 1. The positive electrode mix 1 formed by mixing the silver oxide powders of the above size with a conductive material and a binder and molding them into a pellet shape is enclosed in the positive electrode can 3, the negative electrode mix 2 formed by mixing zinc in power form with a gelling agent and electrolytes and molding them into a pellet shape is enclosed in the negative electrode cup 6, and the positive electrode mix 1 and the negative electrode mix 2 are stacked with the separator 4 between them. Further, a solution of potassium hydroxide and a solution of sodium hydroxide that have high concentrations are added as the electrolytes, and the positive electrode can 3 and the negative electrode cΕp 6 are caulked via a sealing gasket 5 to form the battery.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a silver oxide battery,
More specifically, it relates to silver oxide powder that improves the characteristics of a silver oxide battery.

[0002]

2. Description of the Related Art Silver oxide batteries are widely used as a power supply for small electronic devices such as electronic wrist watches and electronic desk calculators, and the demand for silver oxide batteries is increasing with the spread of these small electronic devices. .

This silver oxide battery uses zinc as a negative electrode active material, silver oxide as a positive electrode active material, and uses a high-concentration potassium hydroxide solution, sodium hydroxide solution, or the like as an electrolytic solution. Specifically, granular zinc is mixed with a gelling agent and an electrolytic solution to form a negative electrode mixture, which is stored in a negative electrode cup, and silver oxide powder is mixed with a conductive material and a binder to form pellets. The positive electrode mixture formed into a shape is housed in a positive electrode can, and the negative electrode mixture and the positive electrode mixture are laminated via a separator. A battery is formed by caulking a negative electrode cup containing the negative electrode mixture and a positive electrode can containing the positive electrode mixture via a sealing gasket.

Conventionally, the silver oxide powder of such a silver oxide battery has an average particle diameter of 1 to 10 μm and a bulk density of 0.8 to 1.
The range of 2 g / cm ³ is used. When such a silver oxide powder is used, when the battery is discharged, the resistance of the positive electrode mixture is not sufficiently reduced due to the change of silver oxide into silver due to the discharge reaction, and zinc is changed into zinc oxide. Due to the increase in the resistance of the negative electrode mixture, the electrical characteristics sometimes deteriorated. Also, in terms of battery capacity, since the bulk density of the silver oxide powder is low, it is difficult to mold a high-density positive electrode mixture, and it is not possible to obtain a sufficient capacity.

[0005]

Therefore, an object of the present invention is to provide a silver oxide battery having a large capacity and excellent electrical characteristics by optimizing the average particle size and bulk density of silver oxide powder. To do.

[0006]

The present invention has been made in view of the above problems, and a negative electrode mixture containing zinc contained in a negative electrode cup and a positive electrode mixture contained in a positive electrode can form a separator. In a silver oxide battery laminated by interposing, silver oxide powder having an average particle size of 10 μm or more and 50 μm or less and a bulk density of 1.2 g / cm ³ or more and 1.7 g / cm ³ or less is used as a positive electrode mixture. Solve the problem.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have made a detailed study to eliminate the drawbacks of conventional silver oxide powders. As a result, the reason why the resistance of the positive electrode mixture in the discharge reaction is insufficiently decreased is that the particle size of the silver oxide powders is small. Was found to be involved.

That is, when the particle size of the silver oxide powder is small, the silver oxide powder easily aggregates, and a large lump of silver and silver oxide mixture is formed by the discharge reaction. At that time, a large space is generated between the agglomerates, the contact between the agglomerates is lowered, and the resistance of the positive electrode mixture is insufficiently lowered. It was considered that, because of the relatively large lumps, a space was generated between the lumps in the discharge reaction, and the decrease in resistance as the positive electrode mixture was also insufficient.

In order to increase the capacity of the battery, one method is to form the positive electrode mixture with a high density, and for that purpose, it is effective to increase the bulk density of the silver oxide powder. I also found

From the above viewpoint, an embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a sectional side view of a configuration example of a silver oxide battery to which the present invention is applied, and FIG. 2 is a sectional side view of a configuration of a test cell.

First, as described above, a silver oxide battery is a battery that uses zinc as a negative electrode active material, silver oxide as a positive electrode active material, and a high-concentration potassium hydroxide solution, sodium hydroxide solution, or the like as an electrolytic solution. As shown in FIG. 1, a positive electrode mixture 1 formed by mixing silver oxide powder with a conductive material and a binder and molding it into a pellet is housed in a positive electrode can 3, and granular zinc is used as a gelling agent and The negative electrode mixture 2 formed by mixing with the electrolytic solution and forming into a pellet is housed in the negative electrode cup 6, and the positive electrode mixture 1 and the negative electrode mixture 2 are laminated via the separator 4. Further, the positive electrode can 3 and the negative electrode cup 6 are caulked with the sealing gasket 5 interposed therebetween to form a battery.

The present invention is a positive electrode mixture 1 for the above-mentioned silver oxide battery.
In the above, the silver oxide powder having an average particle diameter of 10 μm or more and 50 μm or less and a bulk density of 1.2 g / cm ³ or more and 1.7 g / cm ³ or less is used. The silver oxide powder can be easily obtained by controlling reaction conditions such as reaction time and reaction temperature in the reaction represented by the reaction formula (1). 2AgNO ₃ + 2KOH → Ag ₂ O + KNO ₃ + H ₂ O (1)

By using the silver oxide powder having an average particle size of 10 μm or more and 50 μm or less, the silver oxide powder is less likely to agglomerate, and a sponge-like silver / silver oxide mixture is formed by the discharge reaction. Therefore, a silver network having extremely high conductivity is formed, and the resistance as the positive electrode mixture is sufficiently reduced.

Further, the bulk density is 1.2 g / cm ³ or more,
By using a silver oxide powder of 1.7 g / cm ³ or less, it becomes easy to mold a high density positive electrode mixture, and it is possible to manufacture a silver oxide battery having a large capacity and excellent electrical characteristics.

The silver oxide powder having a bulk density of less than 1.2 g / cm ³ has an average particle size of 10 μm or less, and the silver oxide powder is apt to agglomerate. A mixture is formed, the resistance of the positive electrode mixture is not sufficiently reduced, and it becomes difficult to increase the density. On the other hand, if the bulk density exceeds 1.7 g / cm ³ , it is difficult to generate it by the method of the above reaction formula (1) effective for producing silver oxide powder.

Next, examples of the present invention will be described based on the experimental results.

Example 1 A silver oxide battery was prepared as follows. First, silver oxide powder having an average particle size of 20 μm and a bulk density of 1.6 g / cm ³ is mixed with a conductive material and a binder, and the mixture is molded into a pellet to prepare a positive electrode mixture. The agent was stored in a positive electrode can (positive electrode terminal). This positive electrode can is made by pressing a nickel-plated stainless steel plate having a predetermined thickness into a predetermined shape.

Further, zinc powder was mixed with a gelling agent and an alkaline electrolyte, and the mixture was molded into pellets to prepare a negative electrode mixture, and this negative electrode mixture was stored in a negative electrode cup (negative electrode terminal). This negative electrode cup is a three-layer clad plate of copper, stainless steel and nickel having a predetermined thickness, which is pressed into a predetermined shape.

Thereafter, the positive electrode mixture and the negative electrode mixture described above were laminated with a separator consisting of three layers of a non-woven fabric, cellophane, and a polyethylene graft-polymerized membrane sandwiched therebetween, and the positive electrode can and the negative electrode cup were made of nylon. By caulking through the gasket, the outer diameter is 11.6 mm and the height is 3.0 m
m were prepared.

Examples 2 to 6 Silver oxide batteries were prepared in the same manner as in Example 1 except that the silver oxide powder used in the positive electrode mixture had the average particle size shown in Table 1.

[0021]

[Table 1]

Comparative Example 1 A silver oxide battery was produced in the same manner as in Example 1 except that silver oxide powder having an average particle size of 8 μm and a bulk density of 1.0 g / cm ³ was used as the positive electrode mixture.

The internal resistance of the battery manufactured as described above was evaluated. The internal resistance of the battery is 20
Evaluation was performed by measuring with a sine wave alternating current method (1 KHz) at ℃. The internal resistance was measured at a depth of discharge of 0%, 4
It was carried out at 0% and 80%, respectively. Also,
The number of batteries used for the measurement was 20 each, and the data is an average value thereof. The results of measuring the internal resistance of Examples 1 to 6 and Comparative Example 1 are shown in Table 1 above.

As can be seen from Table 1, when the average particle size of the silver oxide powder is less than 10 μm, the internal resistance of the battery is found to increase in the range of 40% to 80% of the depth of discharge.
On the other hand, also when the average particle diameter exceeds 50 μm, it was similarly confirmed that the internal resistance increased in the range of the discharge depth of 40% to 80%. As described above, as a cause of these, when silver oxide powder having an average particle diameter of less than 10 μm is used, the silver oxide powder aggregates and the decrease in the resistance of the positive electrode mixture due to the discharge reaction becomes insufficient. It is considered that when a material having a diameter of more than 50 μm is used, a space is generated between the lumps due to the discharge reaction due to the relatively large lumps themselves, and the reduction of the resistance as the positive electrode mixture becomes insufficient. .

Examples 7 to 14 As the silver oxide powder used in the positive electrode mixture, those having a bulk density shown in Table 2 were used, and the same size was obtained under the same positive electrode mixture forming conditions as in Example 1. The amount of the positive electrode mixture was adjusted, and the same capacity as the increased capacity of the positive electrode mixture was added to the negative electrode mixture to prepare a silver oxide battery. These silver oxide batteries were tested with a test cell for inspecting the electric capacity of the positive electrode active material shown in FIG.

[0026]

[Table 2]

In FIG. 2, the same symbols as those in FIG. 1 represent the same members. Reference numeral 7 in FIG. 2 is a polytetrafluoroethylene O-ring for pressing the negative electrode cup 6, reference numeral 8 is an acrylic resin upper lid for pressing the O-ring 7, and reference numeral 10 is a positive electrode mixture. It is a positive electrode case made of stainless steel for storing. Reference numeral 9 is a fixing screw for fixing the upper lid 8 to the positive electrode case 10. Further, the change in the amount of the negative electrode mixture was dealt with by changing the thickness of the bottom portion of the sealing gasket 5.

The battery manufactured as described above (Examples 7 to 7)
Regarding Example 14), the discharge capacity and the internal resistance were measured. Battery discharge capacity is temperature 20 ℃, load resistance 30KΩ
Discharge was carried out, and the electric capacity was measured at a final voltage of 1.4V. The number of batteries used for the measurement was 20 each, and the data was the average value thereof. The evaluation of the internal resistance was performed by the same method as described above. The measurement result of the discharge capacity of the battery is shown in Table 2 above, and the measurement result of the internal resistance is shown in Table 3.

[0029]

[Table 3]

As can be seen from Table 2, a decrease in capacity was observed as the bulk density of the silver oxide powder decreased. This is because, as described above, as the bulk density of the silver oxide powder decreases, it becomes difficult to mold a high-density positive electrode mixture.

Next, as can be seen from Table 3, when the bulk density of the silver oxide powder was less than 1.2 g / cm ³ , it was recognized that the internal resistance of the battery increased in the range of the discharge depth of 40% to 80%. . This is because the silver oxide powder having a bulk density of less than 1.2 g / cm ³ has a small average particle size of 10 μm or less. Probably because it became enough.
In addition, silver oxide powder having a bulk density of more than 1.7 g / cm could not be produced.

As described above, it is appropriate that the silver oxide powder used in the positive electrode mixture has an average particle size of 10 μm or more and 50 μm or less and a bulk density of 1.2 g / cm ³ or more and 1.7 g / cm ³ or less. It has been shown.

[0033]

As described above, according to the present invention,
In silver oxide batteries, the positive electrode mixture has an average particle size of 10 to 50 μm.
By using a silver oxide powder having a m and a bulk density of 1.2 to 1.7 g / cm ^3, a silver oxide battery having excellent electric characteristics and a large capacity can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional side view of a configuration example of a silver oxide battery to which the present invention has been applied.

FIG. 2 is a sectional side view of the configuration of the test cell.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Positive electrode mixture, 2 ... Negative electrode mixture, 3 ... Positive electrode can, 4 ... Separator 5 ... Sealing gasket, 6 ... Negative cup, 7 ... O-ring, 8 ... Top lid 9 ... Fixing screw, 10 ... Positive electrode case

Claims (2)

[Claims] 1. A silver oxide battery using silver oxide powder as a positive electrode active material, wherein the silver oxide powder has an average particle size of 10 μm or more and 50 μm or less. 2. The bulk density of the silver oxide powder is 1.2 g / c.
m ³ or more, and characterized in that 1.7 g / cm ³ or less, silver oxide battery as claimed in claim 1.