JPH0831425A - Battery - Google Patents

Abstract

(57) [Summary] [Purpose] The objective is to improve the deterioration of discharge performance due to long-term storage of air batteries. [Composition] Mn ₃ O ₄ of manganese oxide is used as a catalyst for a positive electrode using oxygen as an active material, and its specific surface area is 1
5 to 30 m ² / g, or by using an average particle size of 10 μm or less, it is stable against alkaline aqueous solution,
Further, the present invention provides an air battery having excellent discharge characteristics after storage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery using an air electrode containing manganese oxide as one of its constituent elements as a positive electrode.

[0002]

2. Description of the Related Art Conventionally, a battery of this type was produced by heat treating γ-MnOOH at a temperature of 250 to 450 ° C. and mixing the produced manganese oxide with activated carbon powder, a fluororesin binder and a conductive material. An air electrode was used (for example, JP-A-59-171468).

[0003]

When the manganese oxide produced by this conventional method is used, the manganese oxide is altered by the electrolytic solution composed of an aqueous solution containing potassium hydroxide as a main component, and high-efficiency discharge cannot be performed. There was a problem.

The above problem occurs due to the following reasons.
That is, in the manganese oxide produced by heat-treating γ-MnOOH, about 75% of the total weight is occupied by Mn ₅ O ₈ , and the remaining about 25% is occupied by Mn ₃ O ₄ . The main component here is Mn
₅ O ₈ is susceptible to alteration by the electrolytic solution containing potassium hydroxide as a main component, causing a decrease in the specific surface area required for the catalytic function, which prevents high-efficiency discharge.

[0005]

In order to solve these problems, the present invention uses a catalyst having a specific surface area of 15 to 25 m ² /
g, or Mn ₃ O ₄ having an average particle diameter of 10 μm or less is used to manufacture an air electrode, and the air electrode is used as a positive electrode to manufacture a battery to increase the amount of electricity discharged under high load.

[0006]

According to this constitution, Mn ₃ O ₄ forming the catalyst does not react with the electrolytic solution containing potassium hydroxide as a main component to reduce the specific surface area, and the catalytic ability is maintained well. It is possible to increase the amount of electricity discharged from an air battery using this air electrode using Mn ₃ O ₄ as a positive electrode.

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 (A) shows a structural cross-sectional view of an AA-type zinc-air battery used in an embodiment of the present invention. As shown in FIG. 1 (B) in an enlarged manner, 4 in the figure is a catalyst layer 1, a current collector 2,
And an air electrode having a three-layer structure constituted by the gas diffusion layer 3 and characterized by the present invention.

For the air electrode 4, a sheet of the catalyst layer 1 is pressure-bonded to both sides of the current collector 2 in which a stainless wire having a wire diameter of about 0.15 mm is woven and nickel-plated to have a mesh of 40 mesh. This catalyst layer sheet was prepared by mixing 1.5 kg of carbon black, 4.5 kg of activated carbon, 6 kg of manganese oxide and 0.88 kg of fluororesin powder, adding 25 kg of water to this mixture, kneading the mixture, and extruding it into a flat strip shape. Further, the sheet was rolled between two rolling rollers heated to about 60 ° C. and rolled into a 0.6 mm sheet. A flat plate composed of the catalyst layer 1 and the current collector 2 is curved and a part of both ends is overlapped to form a cylindrical shape. Then, a part of the catalyst layer 1 is removed and the current collector 2 is exposed to serve as a terminal. Next, carbon black and fluororesin are kneaded using water and a polyoxyethylene alkyl ester-based surfactant, and a sheet of the gas diffusion layer 3 formed into a sheet shape of about 200 μm is wound from the outside. The number of windings at this time was two or more.
Through the above steps, a cylindrical air electrode having a three-layer structure is manufactured. 5 is a separator in which cellophane is laminated on a vinylon nonwoven fabric. No. 6 was gelated by adding 3 wt% of sodium polyacrylate and 1 wt% of carboxymethyl cellulose to 40 wt% potassium hydroxide aqueous solution (containing 3 wt% of zinc oxide). In addition, the gelled zinc negative electrode was mixed, and its theoretical capacity was 3700 mAh. 7 is an air diffusion paper, 8 is a positive electrode can, and 9 is an insulating tube. Further, 10 is an air intake hole, 11 is a hermetic seal to be peeled off before using the battery, 1
Reference numeral 2 is a dish paper, and 13 and 14 are metal caps, and an exposed collector serving as a terminal of a cylindrical air electrode is sandwiched between them and crimped, and this is spot-welded to the positive electrode can 8.
Reference numeral 15 is an organic sealant, 16 is a synthetic resin sealing body, 17 is a negative electrode terminal cap, and 18 is a nail-shaped negative electrode current collector.

(Experimental Example 1) The effect of alkali resistance of various manganese oxides will be described with experimental examples. Classify the particle size range of various manganese oxides to a particle size of 10 μm or less, and
0 wt% potassium hydroxide aqueous solution (3 wt% zinc oxide
The results of the discharge capacity of the air batteries produced by using various manganese oxides at 60 ° C. for 5 days in a sealed state and continuously discharged at 500 mA. It shows in Table 1.

[0011]

[Table 1] In Table 1, MnO ₂ , is Mn ₅ O ₈ , is Mn ₅ O ₈ and M
Mn is a mixture of n ₃ O ₄ and M _{3 in a} weight ratio of 3: 1.
₃ O ₄ . Each manganese oxide was immersed in the above alkaline aqueous solution for 5 days, washed with water and dried to obtain powder X.
When the respective changes were examined by the line diffraction pattern, it was found that in, the manganese oxide was reacted with potassium hydroxide to generate KMnO ₂ . However, there was no change before and after immersion. From this,
It can be seen that Mn ₃ O ₄ is stable to a 40 wt% potassium hydroxide aqueous solution (containing 3 wt% zinc oxide).

Further, the discharge capacity is 720 mAh,
980mAh, is 1220mAh, is 2550mAh
h, and in the case of ~, the catalytic ability of manganese oxide was lost.
It is thought that the discharge characteristics deteriorated and the discharge characteristics deteriorated. one
If the manganese oxide does not deteriorate, the catalytic ability does not decrease.
Therefore, it is considered that the discharge characteristics were good. (Experimental example 2) Mn₃O_FourThe specific surface area and average particle size of
The reason for limitation will be described with an experimental example. Difference in average particle size
Become Mn₃O_FourTo reduce γ-MnOOH to produce
250, 300, 350, 400, 4 in the atmosphere
Baking was performed at each temperature of 50 ° C. for 2 hours or more. Made at each firing temperature
The produced manganese oxide was Mn by powder X-ray diffraction measurement.
₃O_FourWas confirmed. After that, each Mn₃O_FourRatio table
Area (Nikkiso-4201 Model Micro Truck Bae
Tasobe automatic surface area meter),
In order of degrees 30, 24, 15, 7, 3m²/ G. Well
Particle size distribution (JEOL / JEOL-laser diffraction particle size
The result of measurement with a distribution measuring device is that the average particle size is 2 in order,
It became 6, 10, 17, and 18 μm. And each manga
Oxides a, b, c, d, e, activated carbon powder and fluorine
An air electrode is prepared by mixing with a fat binder and a conductive material,
Further, using them, batteries A, B, C, D and E were produced.
Was. Put those batteries in an atmosphere of 20 ° C and 40% relative humidity.
In the air, the result of the discharge electricity quantity of continuous discharge of 500mA
2 and 3 show. From FIG. 2, the specific surface area is 15 to 30 m.
²Batteries using manganese oxide / g have a discharge electricity of 23
It is possible to discharge more than 00mAh, which is very effective for discharge characteristics.
I know there is. Further, from FIG. 3, the average particle size is 10μ.
Batteries using manganese oxide of m or less can also discharge electricity of 23
It discharges more than 00mAh and is effective in improving discharge characteristics.
I understand that

[0013]

As described above, according to the present invention, the catalyst has a specific surface area of 15 to 30 m ² / g or an average particle size of 10 μm.
By using an air electrode using Mn ₃ O ₄ of m or less for the positive electrode, a battery excellent in high efficiency discharge characteristics can be realized.

[Brief description of drawings]

FIG. 1A is a half sectional view of the configuration of a cylindrical zinc-air battery in an embodiment of the present invention. FIG.

FIG. 2 is a diagram showing a relationship between a specific surface area of manganese oxide which is a catalyst of a battery and an amount of discharged electricity in an example of the present invention.

FIG. 3 is a graph showing the relationship between the average particle size of manganese oxide, which is the catalyst of the battery, and the amount of discharged electricity in the example of the present invention.

[Explanation of symbols]

 1 Catalyst Layer 2 Current Collector 3 Gas Diffusion Layer 4 Cylindrical Air Electrode 5 Separator 6 Gel Zinc Negative Electrode 7 Air Diffusion Paper 8 Positive Electrode Can 9 Insulating Tube 10 Air Intake Hole 11 Seal Seal 12 Metal Bottom Cup 13 Metal Outer Cup 14 Metal In-house cup 15 Sealant 16 Resin molding 17 Bottom plate 18 Current collector 19 Porous membrane

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Rin Ota 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (2)

[Claims] 1. An air electrode using Mn ₃ O ₄ as a catalyst is used for a positive electrode that causes an electrochemical reaction on the electrode using oxygen as an active material, and an aqueous solution containing zinc and potassium hydroxide as main components is electrolyzed for the negative electrode. Batteries used for each liquid. 2. A catalyst having a specific surface area of 15 to 30 m ² /
A battery in which an air electrode using Mn ₃ O ₄ having an average particle size of 10 μm or less is used as a positive electrode, zinc is used as a negative electrode, and an aqueous solution containing potassium hydroxide as a main component is used as an electrolytic solution.