JPS58163172A - Alkaline zinc storage battery - Google Patents

Abstract

PURPOSE:To secure an alkaline zinc storage battery that shows excellent cycle and capacity characteristics, by containing a wettable material entwined with a high conductive carbon fiber, together with zinc active materials in a zinc electrode. CONSTITUTION:Water is added to a mixed powder comprising zinc oxide, metal zinc dust, cadmium oxide as an additive, a mixture of titanium oxide and carbon fiber as a wettable material and fluorocarbon resin as a bonding agent, and thereby a past sheet is produced after kneading. This sheet is struck to both faces of a collector body composed of copper and the like, then press-molded and dried up, thus a zinc electrode is produced. In this connection, a mixed ratio between the titanium oxide and the carbon fiber is 1:1 or 3:1 recommendable. For the manufacturing method, after the titanium oxide is mixed and kneaded in a solvent (water or an organic solvent), the carbon fiber is mixed therein and further mixed and kneaded, then dried up and pulverized. In this case, it is allowable to directly mix and pulverize the titanium oxide and the carbon fiber either. Combining the titanium oxide obtained in this way and a publicized sintering type nickel electrode together, a nickel zinc storage battery A is produced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to alkaline zinc storage batteries that use zinc as a negative electrode active material, such as nickel-zinc storage batteries and silver-zinc storage batteries.

Zinc as a negative electrode active material has the advantage of having a high energy density per unit weight and being inexpensive, but on the other hand, since zinc is deposited in a dendritic or spongy form during charging, repeated charging and discharging will result in electrolytic zinc. has the disadvantage that it penetrates the separator and comes into contact with the opposite electrode, causing an internal short circuit.

In order to deal with this problem, a method has been proposed in which multiple types of separators are combined and the amount of electrolyte is regulated.

This method alleviated the deterioration caused by internal short circuits caused by deposited zinc.

However, since the amount of electrolyte is regulated, the electrolyte is unevenly distributed in the zinc electrode, resulting in a reduction in the reaction surface area, making it impossible to obtain satisfactory discharge capacity and cycle life, and also having the disadvantage that charging and discharging efficiency is reduced.

The present invention was invented in view of the above points, and includes a zinc electrode containing a wettable substance entangled with carbon fibers, and due to the presence of the wettable substance entangled with carbon fibers,
The purpose is to increase the electrolyte retention + ÷ ability of the zinc electrode to uniformly distribute the electrolyte and improve conductivity. Wetting substances include oxides or hydroxides such as titanium and zirconia, and carbon fibers are made by carbonizing cellulose fibers or vinylon fibers by heating and firing them in an inert atmosphere at 1000°C. It is highly conductive.

An embodiment of the present invention will be described below.

From 75% by weight of zinc oxide powder, 10% by weight of metallic zinc powder, 5% by weight of cadmium oxide as an additive, 5% by weight of a mixture of titanium oxide and carbon fiber as a wetting substance, and 5% by weight of fluororesin powder as a binder. After adding water to the mixed powder and kneading it, a paste sheet is created using a roller. This sheet is attached to both sides of a current collector made of copper or the like, molded under pressure, and dried to produce a zinc electrode. The mixing ratio of titanium oxide and carbon fibers may range from 1:1 to 6:1, but in the example, it was set to 1:1. As a manufacturing method, titanium oxide is kneaded in a solvent (water or an organic solvent), carbon fibers are mixed therein, further kneaded, and then dried and pulverized. Alternatively, titanium oxide and carbon fiber may be directly mixed and pulverized.

A nickel-zinc storage battery (A) is made by combining the zinc electrode obtained by pressing in this way and a known sintered nickel electrode. (3) is a separator, (4) is a liquid retaining layer, (5) is a battery case, ( 6) is a battery case lid, and +71 and +81 are positive and negative terminals.

For comparison, the same comparison as the other I:IJ example was made, except that titanium oxide and carbon fiber were not contained, and the amount of zinc oxide powder was increased by the content of titanium oxide and carbon fiber in the example. A battery (B) was created.

FIG. 2 is a cycle characteristic diagram of the storage battery (A) according to the present invention and the comparative battery (B). The charge/discharge cycle conditions are 1
After charging at 50 mA for 5 hours, the battery was discharged at 151] mA, and discharging was stopped when the battery voltage reached 1.2 mA. As is clear from Fig. 2, the storage battery according to the present invention (Kawa) is superior in cycle characteristics and capacity characteristics compared to the comparative battery (B). Titanium increases the electrolyte retention ability of the zinc electrode, and distributes the electrolyte uniformly in the zinc electrode.
It is also thought that this is because the carbon fibers enhance the conductivity of the zinc electrode.

As described above, the present invention includes a zinc active material in a zinc electrode,
By containing a wettable substance entangled with highly conductive carbon fibers, an alkaline zinc storage battery exhibiting excellent cycle characteristics and capacity characteristics can be obtained, and its industrial value is great.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of an alkaline zinc storage battery according to the present invention, and FIG. 2 is a cycle characteristic diagram of the storage battery according to the present invention and a comparative battery. (1)...Zinc electrode.

Claims (1)

[Claims] (1) Alkaline zinc storage battery with zinc electrodes containing a wettable material entangled with carbon fibers.