ELECTRODE FOR LEAD STORAGE BATTERY AND MANUFACTURING METHOD

THEREOF

Technical Field

The present invention relates to an electrode for lead storage battery and a method for preparing the same. More particularly, it relates to an electrode for lead storage battery prepared by using additional additives in preparation of a paste for electrodes, through the improvement of the paste for electrodes prepared by mixing and kneading lead powder with sulfuric acid in the prior art, and a method for preparing the same.

Background Art

In the prior art, electrodes for lead storage battery has been prepared by applying a lead powder paste formed by mixing and kneading lead alloy excellent corrosion resistance against sulfuric acid with sulfuric acid and lead powder. More particularly, lead powder comprising lead oxide as a main ingredient is kneaded with sulfuric acid to form a lead powder paste (mixing and kneading step) . The lead powder paste is applied on a latticed current collector substrate and cured and dried under predetermined conditions (curing and drying step) . The substrate is dipped in an electrolyte for application of an electric current to form a substrate comprising an active material with electro-chemical activity (chemical conversion step) .

However, in case of the electrode prepared by applying the lead powder paste formed with only sulfuric acid and lead powder, as charge and discharge are repeated, the active

material in the substrate reacts with sulfuric acid in the electrolyte to form lead sulphate, which forms a thin film on the substrate. The thin film is ultimately separated from the substrate and corroded, causing weakening of electromotive force and increase of internal resistance and thereby, reduction of life span of battery.

Disclosure of Invention Technical Problem

Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the conventional art, and it is a primary object of the present invention to provide an electrode for lead storage battery by using a specific additive in the preparation of a lead powder paste to prevent the lead powder from reacting with sulfuric acid to form lead sulphate, and a method for manufacturing the same.

Technical Solution

To accomplish the above objects of the present invention, according to the present invention, there is provided an electrode for lead storage battery prepared by applying a paste containing lead powder on a substrate, in which the paste is prepared by mixing and kneading 20 to 50 weight parts of an additive mix comprising sodium hydrogen sulphate, antimony, magnesium, aluminium sulphate and diluted sulfuric acid with 100 weight parts of lead powder. Here, the additive mix comprises 10 wt% to 20 wt% of sodium hydrogen sulphate, 12 wt% to 20 wt% of antimony, 15 wt%

to 20 wt% of magnesium, 10 wt% to 20 wt% of aluminium sulphate and 10 wt% to 30 wt% of diluted sulfuric acid.

Also, in the method for manufacturing an electrode for lead storage battery comprising the step of applying a paste containing lead powder on a substrate according to the present invention, the paste is prepared by mixing and kneading 20 to 50 weight parts of an additive mix comprising sodium hydrogen sulphate, antimony, magnesium, aluminium sulphate and diluted sulfuric acid with 100 weight parts of lead powder. Here, the additive mix comprises 10 wt% to 20 wt% of sodium hydrogen sulphate, 12 wt% to 20 wt% of antimony, 15 wt% to 20 wt% of magnesium, 10 wt% to 20 wt% of aluminium sulphate and 10 wt% to 30 wt% of diluted sulfuric acid

Advantageous Effects

The electrode for lead storage battery according to the present invention can be shallow charged in a short time. Also, since a thin film is formed to prevent corrosion of the electrode plates and to remove white lead sulphate, thereby extending life span of the storage battery. Further, according to the present invention, the use of sulfuric acid which causes environmental pollution is retrenched and thus, it is possible to prepare an environmentally friendly lead storage battery.

Description of the Drawings

Further objects and advantages of the invention can be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a graph showing the procedures through which the electrodes according to the example of the present invention and comparative example reach 12 V upon the initial charge; FIG. 2 is a cjraph showing the discharge capacity of the electrode according to the example of the present invention when the electrode is repetitively charged and discharged; and

FIG. 3 is a graph showing the discharge capacity of the electrode according to the comparative example when the electrode is repetitively charged and discharged.

Best Mode

According to the present invention, the method for manufacturing an electrode for lead storage battery according to the present invention comprises the step of applying a paste containing lead powder on a substrate according to the present invention, in which the paste containing lead powder is prepared by mixing and kneading 20 to 50 weight parts of an additive mix comprising sodium hydrogen sulphate, antimony, magnesium, aluminium sulphate and diluted sulfuric acid with

100 weight parts of lead powder.

Here, it is preferred that the additive mix comprises 10 wt% to 20 wt% of sodium hydrogen sulphate, 12 wt% to 20 wt% of antimony, 15 wt% to 20 wt% of magnesium, 10 wt% to 20 wt% of aluminium sulphate and 10 wt% to 30 wt% of diluted sulfuric acid.

Also, according to the present invention, the electrode for lead storage battery prepared by applying a paste containing lead powder on a substrate, in which the paste

containing lead powder is prepared by mixing and kneading 20 to 50 weight parts of an additive mix comprising sodium hydrogen sulphate, antimony, magnesium, aluminium sulphate and diluted sulfuric acid with 100 weight parts of lead powder. Here, the additive mix comprises 10 wt% to 20 wt% of sodium hydrogen sulphate, 12 wt% to 20 wt% of antimony, 15 wt% to 20 wt% of magnesium, 10 wt% to 20 wt% of aluminium sulphate and 10 wt% to 30 wt% of diluted sulfuric acid.

As described above, the features of the present invention is the use of an additive mix with reduced acidity comprising sodium hydrogen sulphate, antimony, magnesium, aluminium sulphate and sulfuric acid (diluted sulfuric acid) which have not be used in the prior art.

The weight ratio of the lead powder and the additive mix is preferably 20 to 50 weight parts of the additive, based on 100 weight parts of the lead powder. If the weight ratio of the additive mix to the lead powder is less than 20 weight parts, the effect of the additive mix preventing the reduction of the electromotive force is not prominent. If the weight ratio of the additive mix to the lead powder exceeds 50, the conversion coating efficiency is deteriorated.

Here, the mixing ratio of the additive mix is, as described above, preferably 10 wt% to 20 wt% of sodium hydrogen sulphate, 12 wt% to 20 wt% of antimony, 15 wt% to 20 wt% of magnesium, 10 wt% to 20 wt% of aluminium sulphate and 10 wt% to 30 wt% of diluted sulfuric acid. Though this mixing ratio is the experimentally obtained ratio for the optimal result, the present invention is not limited to the above ratio. Even when a small amount of any one component is added, the effect is better than when only sulfuric acid is added.

Meanwhile, the sulfuric acid is used as a diluted sulfuric acid, preferably 20% to 60%.

According to the present invention, sodium hydrogen sulphate is used to form a thin film for prevention of an active material, antimony and magnesium are used to increase current efficiency and aluminium sulphate is used to remove generated lead sulphate. However, it is believed roles of respective components are not limited to the above-described but are determined by interactions between them, which is not clearly examined. Though the correct reaction mechanism to prove the effect of the present invention obtained by using the foregoing components show is not presented, the completion of the present invention is not hindered.

Meanwhile, types of the substrate which is usable in the present invention and the preparation method of lead powder and processes performed in various steps for preparing electrodes are not particularly limited. For example, the curing and drying step performed after applying the lead powder paste can be performed by low temperature curing or high temperature curing. Also, an additional additive for increasing the conversion coating efficiency can be added in the conversion coating formation process without departure of the scope of the present invention. However, when the electrode according to the present invention is used in an electrolyte containing the additive mix as specified according to the present invention not in a common sulfuric acid electrolyte, significant effect can be expected.

Mode for Invention

Now, the electrode for lead storage battery and the method for preparing the same according to the present invention are described in detail.

[Example] A substrate of lead alloy was prepared. 1 Kg of lead powder prepared according to the baron method was mixed with 0.3 Kg of the additive mix comprising 16 wt% of sodium hydrogen sulphate, 18 wt% of antimony, 16 wt% of magnesium, 20 wt% of aluminium sulphate, and 30 wt% of sulfuric acid (27% diluted sulfuric acid) , followed by kneading to form the lead powder paste. The obtained lead powder paste was applied on the substrate and the substrate was cured at 90 ^° C for 3 hours and 30 minutes and dried for 3 days. An electric current was applied through the dried substrate to complete the formation of the electrode.

[Comparative Example]

This comparative example was performed by following the same procedures as described in Example 1 to prepare an electrode, except that sulfuric acid was used in stead of the additive mix according to the present invention.

FIG. 1 is a graph showing the procedures through which the electrodes according to the example of the present invention and comparative example reach 12 V upon the initial charge. As shown in FIG. 1, the electrode according to the Example needed 34 hours to reach 12V and the electrode according to the Comparative Example needed 72 hours.

FIG. 2 is a graph showing the discharge capacity of the electrode according to the example of the present invention when the electrode is repetitively charged and discharged FIG. 3 is a graph showing the discharge capacity of the

electrode according to the comparative example when the electrode is repetitively charged and discharged

As shown in FIGs. 2 and 3, it was found that the time needed until the voltage dropped under 1.8 V was much longer in the electrode according to the Example. Also, as the number of charge and discharge was increased, the discharge capacity was nearly the same in the Example according to the present invention but it was significantly reduced in the

Comparative Example. This means that the electrode according to the Example was not corroded since lead sulphate was accumulated.

Industrial Applicability

The electrode for lead storage battery according to the present invention can be shallow charged in a short period of time since it has a high current efficiency. Also, a thin film is formed to prevent corrosion of electrode plates and to remove white lead sulphate, thereby extending life span of the storage battery. Further, according to the present invention, the use of sulfuric acid which causes environmental pollution is retrenched and thus, it is possible to prepare an environmentally friendly lead storage battery.

While the present invention has been described with reference to the particular illustrative embodiments, it is not to be restricted by the embodiments but only by the appended claims. It is to be appreciated that those skilled in the art can change or modify the embodiments without departing from the scope and spirit of the present invention.