SU756526A1 - Electrode for alkaline storage battery and method of manufacturing same - Google Patents

Description

The invention relates to chemical current sources, and more specifically to alkaline batteries with cadmium and zinc anodes, the characteristics of which largely depend on the presence in the active mass of surface-active organic substances that simultaneously possess the properties of binders.

Electrodes of alkaline accumulators are known, for example, zinc and cadmium, whose active masses are made of a mixture of basic components and binding agents, which at the same time are stabilizers 1; capacitance of the electrode, such as sodium salt of lignosulfonic acid [1}.

These electrodes are made by pressing water-based paste on a current-collecting base using 2 (

alkaline paper envelope. Additives are well soluble in the electrolyte and undergo oxidation during battery operation; therefore, their stabilizing effect on the characteristics of the battery quickly weakens. At the same time there is an accumulation of carbonates in the electrolyte.

In this regard, the electrode manufactured using such a binder L

2

substances characterized by a short service life and low utilization of cadmium and zinc.

Closest to the invention to the technical essence and the achieved results is an electrode for an alkaline battery containing the main component and a binding additive of polyethylene oxide, polyethylene is also introduced into the active mass.

A method of making an electrode consists in rolling a mixture of the main component with a binder additive of polyethylene oxide £ 2]. Molecular weight of polyethylene oxide does not exceed 10 ⁶ . After rolling, the electrode is sintered.

The presence of inert polyethylene reduces the percentage of active material in the electrode and requires the use of a large amount of an activating additive - polyethylene oxide. in the process of heat treatment of the electrode, polyethylene oxide partially loses its activating properties, ie, a decrease in the degree of polymerization, i.e. molecular weight reduction. This leads to deterioration of electrical characteristics.

In order to improve the electrical characteristics, polyethylene oxide is taken with a molecular weight of 3.5 · 10 ° -10 ⁷ at

756526

the following ratio of components, mass. %;

The main component 97-99,5 Polyethylene oxide 0.5-3.

A method of manufacturing an electrode is characterized in that polyethylene oxide is introduced into the main component in the form of a gel-like aqueous solution with a viscosity of 600-1500 cP, the resulting mixture is dried at 50-70 ° C to a final moisture content of 0.03-0.2% and rubbed through a sieve for obtain conglomerated particles of spherical shape with a size of 0.3 -

1.5 mm.

Zinc or cadmium can be taken as the main component.

An aqueous solution of polyethylene oxide of a given molecular weight has high adhesive properties, which increase in proportion to the increase in molecular weight. A characteristic feature of the new supplement is hers. high adhesion to the active material. The polyethylene oxide is injected in the form of a gel-like aqueous solution with a viscosity of 600-1500 centipoise. After processing the components of the active mass with polyethylene oxide, drying at 50-70 ° C to a final moisture content of 0.03-0.2% for 30-60 minutes and rubbing the active mass through a sieve, a change in the size and shape of the powder particles is observed. So, if the particle size of the powder of metal oxides is 1-3 microns, then after processing it is equal to 0.3-1.5 mm. Particle shape is spherical. All this ensures the rolling mass of the active mass and the high porosity of the finished electrodes.

Polyethylene oxide with a molecular weight of 3.5 · 10 ⁶ is introduced in the amount of 0.5-3.0 wt.%. The fact that polyethylene oxide simultaneously performs the functions of an activating additive and a binder, facilitates the process of manufacturing electrodes both by the rolling method and by pressing and makes it possible to increase the content of the active material in them. The composition of the active mass of the finished electrode contains 97-99.5% of the main component and 0.5-3% polyethylene oxide.

The effect of polyethylene oxide on the characteristics of electrodes is determined by its strong adsorption on the electrode surface by the mechanism of formation of hydrogen bonds. When this occurs, the dispersion of the active mass of zinc and cadmium electrodes and, in addition, the activation of the process of anodic cadmium oxidation occurs. The high molecular weight of the polyethylene oxide used determines its high surface activity and increased chemical resistance as compared with lower molecular weight compounds and provides an effective effect for a long time.

. battery life.

An example. Cadmium electrode sealed silver cadmium battery has the following composition, wt.%:

Cadmium Oxide 92

Nickel oxide hydrate 6.5

Polyethylene oxide 1,5.

This electrode is made as follows.

Prepare a solution of polyethylene oxide by dissolving 5 weight.h. polyethylene oxide molecular weight

3.5-10 ⁶ to 95 weight.h. distilled water until the solid phase disappears (approximately 15 hours). This ensures the required viscosity of the solution, equal to 730-750 SP. Cadmium hydroxide and nickel oxide hydrate, taken in a weight ratio of 1: 0.07, are mixed for 20 minutes and sieved through a sieve (ί 09, add the prepared solution of polyethylene oxide to the mixture of the main components in an amount of 1.5 wt.% Calculated on the dry the polymer is stirred until a homogeneous mass is formed.The resulting mass is dried at 60-70 ° C with occasional stirring to a final moisture content of 0.1%, then the mass is rubbed through a sieve to obtain conglomerated spherical particles with a size of 0.9 mm. heel for continuously moving the dried defatted conductive lattice obtained tape knurled active mass chop with a die at the workpiece electrode to the workpiece whereupon the electrodes are welded by spot welding or roller Current taps.

Tests have shown that the proposed electrode has a capacity of 10% more than the prototype electrode. In addition, it improves its performance in low temperatures and safety in the charged state.

Claims (2)

Claim 1. Electrode for alkaline battery containing the main component and polyethylene oxide binder additive, characterized in that in order to improve electrical characteristics, polyethylene oxide is taken with a molecular weight of 3.5'10 ⁶ -10 ⁷ in the following ratio of components, wt.%: Core component 97-99.5 Polyethylene oxide 0.5-3. 2. A method of manufacturing an electrode according to claim 1 by rolling a mixture of the main component with a binder additive of polyethylene oxide, characterized in that the polyethylene oxide is introduced into the main component in the form