JPS58165249A - Anode plate for alkaline battery - Google Patents

Abstract

PURPOSE:To achieve excellent discharging properties, by previously setting some or all cadmium contained in an anode, as metal cadmium, to heighten the electron conductivity. CONSTITUTION:A mixture, which comprises nickel hydroxide containing a small quantity of cobalt hydroxide, powder of carbonickel, cadmium oxide and press- formed while a nickel net which is to function as a current collector is placed in the center of the mixture, thereby providing an anode. A current is caused to flow from the anode to a nickel plate cathode in an aqueous solution of sodium hydroxide, the specific gravity of which is 1.22, to change almost all the cadmium compound into metal cadmium, thus finishing the anode. The anode plate containing the metal cadmium has high discharge potential and a long discharge time.

Description

[Detailed Description of the Invention] Alkaline storage batteries that use nickel oxide as the active material and cadmium as the negative electrode utilize a mechanism in which oxygen generated from the positive electrode is consumed at the negative electrode during charging, and are completely sealed. It has a feature unparalleled by other secondary batteries:

However, when WI number of unit cells are connected in series, if there are large and small gaps in the W filter between the units, the battery with few valleys during discharge will exceed the normal final voltage and cause so-called overdischarge. It will happen.

When overdischarging, hydrogen is generated from the negative electrode in proportion to the current, and oxygen is generated from the negative electrode, but since the rate of absorption of hydrogen is particularly small at tllIl11 yen, hydrogen is generated in a sealed battery. This must be avoided at all costs. Therefore, as a countermeasure to this problem, a method has been adopted in which a cadmium compound such as cadmium hydroxide or cadmium oxide, which is a heavy substance, is added to the active material used in sealed batteries.

That is, when one discharge reaches the overdischarge region, a reaction occurs in which the cadmium compound is reduced to metal cadmium, and hydrogen generation can be suppressed during this period.

Addition of a cadmium compound also has the effect of increasing the oxygen generation potential during charging and increasing the charging efficiency of the positive electrode.

However, not only is it unnecessary for normal charging and discharging, but the presence of cadmium compounds, which is equivalent to a completely healthy substance, lowers the electric resistance of the positive circle, particularly increases the voltage drop during discharge, and causes active material It also had the disadvantage of lowering the utilization rate.

The present invention solves the above-mentioned conventional drawbacks and makes it possible to create a structure that improves the characteristics of a first-layer alkaline battery containing a cadmium compound. This is based on the fact that by using cadmium, C can be used to increase the electronic conductivity in the positive electrode gatekeeper ζ.Hereinafter, a detailed explanation will be given of the results of the actual displacement and comparison with conventional products.

Practical Example 1: Nickel hydroxide containing a small amount of cobalt hydroxide was 40 [11%] and carbon nickel powder was 85 [1%].
%, cadmium oxide was placed at 15% and □ As an adhesive, a raw material mixture consisting of polyethylene powder and 10% and 1% of cadmium oxide was mixed with a thickness of 1.5fi with a nickel mesh as a current collector sandwiched in the center. A positive electrode with a theoretical capacity of 1.8 μm was manufactured by pressure molding to a size of 50×5 G m.

This was placed in an aqueous sodium hydroxide solution with a specific gravity of 1.22, using nickel as a temporary partner, and an 860 mA battery was used to supply electricity in the cathode direction for 8 hours to convert the cadmium compound in the operation into metallic cadmium. According to the present invention, one rod is four.

Practical example 2: Metal cadmium powder was added instead of cadmium oxide in the atl example, and other compositions were used.

The positive electrode manufactured with the same shape is designated as -).

Furthermore, as a conventional example, a conventional positive 11I (C1) was made which was molded to have the same composition and shape as the positive electrode in Example 1, but was not converted into metallic cadmium.

After charging each spit with a current of 270 mm at a temperature of 25°C for 16 hours using two sintered cadmium negative plates of the same size as mating plates in a potassium hydroxide aqueous solution with a ratio T of 1.25. When discharge was carried out at a current of 1.2 μm, the discharge characteristics as shown in FIG. 1 were obtained.

As is clear from Figure 1, the discharge characteristics of the Maw plates) and φ) containing metal cadmium have a higher discharge potential and a longer discharge time than the conventional positive-temporal () discharge characteristics. It was excellent. Also, the characteristics against overdischarge were also good (previous life).
All were good. The reason for this is not certain, but some of the metal cadmium pre-existing in the positive FJJA plate according to the present invention changes to cadmium hydroxide during normal charging of the positive electrode plate, but all of it changes to cadmium hydroxide. Rather than changing to cadmium hydroxide, some of it remains in the stable state of metallic cadmium and becomes positive.
It is thought that it has a good effect of increasing the conductivity inside.

In the example, the so-called powder press type positive electrode plate, which is manufactured by pressure molding powder of active material, conductive material, etc., was described. Positive [1] If it is temporary, a sintered positive electrode plate made of a porous nickel sintered body impregnated with an active material, a paste type negative plate made of a foamed nickel sheet filled with a paste active material, etc.
It goes without saying that the object of the present invention can be achieved regardless of the difference in structure and manufacturing method.

[Brief explanation of drawings]

Figure 1 shows a comparison of discharge characteristics, where (4) (B) is the positive electrode according to the present invention, and io+ is the gate λ that accepts the conventional positive electrode.
1 Unillustrated call Shun (departure)

Claims (1)

[Claims]! A positive solder for alkaline batteries characterized by containing nickel hydroxide as an active material, and a cadmium compound and metal cadmium as additives. ! , Kinkinriki cadmium, some of the cadmium compounds vi
2. The regular plate for alkaline batteries according to claim 1, which is obtained by changing the plate by vapor chemical reduction. $, An alkaline battery center plate characterized in that metal cadmium is added in the form of cadmium powder together with nickel hydroxide as an active material.