JPS60105172A - Paste type positive plate for alkaline storage battery - Google Patents

Abstract

PURPOSE:To increase performance and productivity of a paste type positive plate by impregnating nickel hydroxide as active material in a sintered substrate using nickel fibers obtained by stick-slip vibration cutting. CONSTITUTION:4-50mu nickel fibers are produced by stick-slip vibration cutting. The nickel fibers are distributed in a desired form and sintered to make a porous sintered substrate. Positive active material mainly comprising nickel hydroxide is impregnated in the sintered substrate, and dried, then the thickness of the impregnated substrate is adjusted to form a paste type positive plate for alkaline storage battery. Since this nickel fiber positive plate does not use a core metal and has high impregnation density of active material, energy density is increased and cost is decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a downstream electrode plate for an alkaline storage battery, particularly a paste-type nickel electrode, and an object of the present invention is to provide a nickel positive electrode plate 'i: 41J with high performance, low cost, and productivity.

Conventionally, as a nickel positive electrode plate for an alkaline storage battery, a sintered type electrode plate in which a porous substrate is filled with an active material, in which nickel powder is sintered into a perforated steel plate or a nickel net, is well known.

This porous substrate is made by simply sintering =7 Kel powder into a perforated W (plate or nickel net).The bond between the nickel powder particles is weak, and if the porosity is made high, they will fall off. The practical limit for porosity is about 80%.

In addition, since these porous substrates have weak bonds between nickel powder particles, they always require a core such as a perforated steel plate or nickel net, which has the disadvantage that the active material filling 1 per unit volume is reduced by the volume of the core. have. Furthermore, as is known, since the pores of the porous material are as small as 10 microns or less, the filling method is limited to a solution impregnation method that involves repeated complicated steps.

In an attempt to improve these drawbacks, a so-called paste method has been developed in which a solid active material is directly filled into, for example, a nickel-plated iron fiber sintered body without a core, or a foamed nickel porous body created by electrolytic nickel plating. Filling methods, etc. are being used. However, the former has problems such as instability of plating, and the latter has problems such as low tensile strength. Another type of plate that is directly filled with a solid active material is the pocket type electrode plate, but this type has a structure in which a perforated steel plate is processed to create a pocket and the active material is filled in the pocket. The volume of the perforated copper plate is large, and the packing density per unit volume is quite low.

The cheapest casting method for metal fibers so far is
Although it is a cutting method, when cutting nickel uQ IA using a commercially available scrubber, the tool wears out rapidly,
Moreover, only an 8'A key with a non-uniform diameter could be made.

However, using self-excited vibration ωJ in turning,
By using the so-called chatter vibration cutting method,
It has become possible to produce uniform nickel microfibers, which was previously impossible.

The row of near fiber 8 can be made by 1 rabbit from about 4μ,
The thinner the a-fiber diameter, the greater the surface area, which improves the active material utilization rate.

On the other hand, as the fiber diameter increases, the surface area decreases and the active material utilization rate definitely decreases, so fibers with a diameter of 50 μm or more have little merit. Considering the pore distribution, tensile strength, and active material utilization rate of the substrate that is easy to fill with active material in practical use, it is 4 to 50.
A value of around μ is desirable. After uniformly distributing the nickel fibers using the airlaid method, the porous substrates shown in a and b in Figure 1 (b is an enlarged view of a) are obtained by sintering the nickel fibers in a high-temperature reducing atmosphere at about 1000'C. .

A porous substrate having a porosity of about 85 to 98% and satisfying practical strength can be obtained by controlling the amount of fiber, sintering temperature, time, etc. This porous substrate is filled with an active material containing nickel hydroxide as a main component and a small amount of cadmium hydroxide or cobalt hydroxide in a eutectic state in a slurry form with a solvent such as water, and then dried and adjusted in thickness. and use it as a positive electrode plate. An embodiment of the present invention will be described in detail below.

The average fiber diameter (a) is 5μ by the chatter vibration cutting method.
(B) 20μ (C) 50μ After distributing 60μ of 41J type nickel #111m by air lading method,
Sintering is performed at 1050° C. for about 60 minutes in a reducing atmosphere to obtain a porous substrate having a thickness of 2 cm and a porosity of 95%.

Approximately 10% by weight of nickel powder is added to a eutectic active material consisting of 94% by mole of nickel hydroxide, 5% by mole of cobalt hydroxide, and 1% by mole of cadmium hydroxide, which have been partially oxidized with ammonium persulfate or potassium persulfate. After mixing thoroughly, about 40% by weight of water and about 2% by weight of carboxymethyl cellulose are further added to form a slurry. After filling the porous substrate with this slurry-like active material DEJ, it was dried and the thickness was adjusted to obtain a positive electrode plate having a thickness of 0.7M.

The packing density of the active material is approximately 1. Temporarily g//cc.

The positive electrode plates of these four persimmons were cut into 4 x 4 cm pieces, filled and roughened in a caustic potassium electrolyte, and the energy density ('nAh7
cc) was measured. For comparison with conventional electrode plates,
Energy density of a nickel powder positive electrode plate with the same dimensions (
mA11/cc) was obtained.

Table 1 shows the specific gravity of 0.1 in a caustic potassium N solution with a specific gravity of 1.24.
After charging for 15 hours at 0 current, 0.2C current TeOV
A comparison of the energy density (mAh) when the roughness is increased to VB + H9/H90 is shown.

Table I (Average value of each 20 samples) From Table 1, thinner fiber porous materials tend to have higher energy density. However, the 60 μ fiber electrode plate is only slightly better than the conventional nickel powder sintered electrode plate, and the
It can be said that a fiber diameter in the μ range is good.

The nickel fiber positive electrode plate of the present invention has an energy density that is approximately 40% higher than that of a conventional nickel powder sintered electrode plate. This is because a core metal is not required and a highly porous substrate can be used, making it possible to pack the active material at high density.

In today's world where batteries are required to be more compact, the industrial value of the high energy density and low cost nickel positive electrode plate has been greatly increased by the electrode plate of the present invention9.
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Claims (1)

[Claims] A paste for alkaline storage batteries characterized by filling a positive electrode active material containing nickel hydroxide as a main component into a porous substrate made by sintering 4μ to 50μ nickel fibers KII created by chatter vibration cutting. Formula positive electrode plate.