JPH0213425B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a grid for lead-acid batteries and a method for manufacturing the same.

Conventional configurations and their problems Lead-acid batteries that use a lattice made of a lead alloy that does not contain antimony have less self-discharge than those made of an alloy that contains antimony, and are less susceptible to electrolyte during use. It is characterized by a small decrease.

Therefore, it can be stored for a long time, and there is no need to replenish distilled water while using the battery.

As a lead alloy that does not contain antimony, a ternary lead-tin-calcium alloy (hereinafter referred to as Pb-Ca-Sn alloy) is generally used.

Until now, lattice bodies have been mainly manufactured by casting, but the Pb-Ca-Sn alloy in the molten state suffers from rapid oxidation loss of Ca, poor melt flow in the mold, and low mechanical strength after solidification. , casting workability was poor.

Therefore, a popular method is to roll a Pb-Ca-Sn alloy into a thin sheet and then expand it.

By the way, one of the disadvantages of lead-acid batteries using Pb--Ca--Sn alloys is that they have poor charge acceptance after being left in a discharged state for a long time, and tend to become unable to be charged.

This is because a high-resistance passive layer is formed at the interface between the positive electrode lattice and the active material.

This phenomenon is particularly likely to occur if the specific gravity of the electrolyte, that is, dilute sulfuric acid, is about 1.05 or less while it is being left.

Therefore, the above drawbacks can be overcome by increasing the sulfuric acid concentration in the electrolyte or by increasing the amount of electrolyte.However, increasing the sulfuric acid concentration leads to a decrease in battery life, and increasing the amount of electrolyte is not recommended. There is a limit to increasing the sulfuric acid concentration unnecessarily, as this will increase the weight of the battery.

On the other hand, it has been found that adding a large amount of tin to the lattice interface changes the properties of the high-resistance layer formed at the interface between the lattice and the active material, dramatically improving recovery after overdischarge. Therefore, methods have been considered in which metal tin or the like is preliminarily sprayed onto the grating surface or deposited by methods such as electrolytic plating.

However, since metallic tin is soluble in sulfuric acid, which is an electrolytic solution, not only does the effect not last, but the eluted tin is absorbed by the load, resulting in a high self-discharge rate or a large decrease in the electrolytic solution. Problems have made this method impractical.

Purpose of the Invention The present invention improves the above-mentioned conventional drawbacks, has excellent charge recovery properties after being left over-discharged, and has self-discharge and
The present invention provides a lattice body for a lead-acid battery in which the amount of electrolyte decreases little.

Structure of the Invention The present invention is a material for a so-called expanded lattice body in which a sheet-like material is expanded into a mesh shape. is 1.5~
20% by weight (hereinafter referred to as %) Pb-Sn alloy layer or
It is characterized by using an integrated Pb-Ca-Sn alloy layer.

Furthermore, the present invention provides a flat rolled material (hereinafter referred to as a slab) made of a Pb-Ca-Sn alloy, on at least one side of which a Pb whose main component is Sn and whose content is 1.5 to 20% is applied.
- Integrating the Sn alloy layer or Pb-Ca-Sn alloy layer,
The object of the present invention is to provide a method for manufacturing a lattice body, which is characterized in that the lattice body is then rolled to a predetermined thickness and then expanded into a mesh shape.

Description of examples Examples of the present invention will be described below.

First, on one side of a continuous slab with a composition of Pb-Ca (0.05%)-Sn (0.5%) with a thickness of 10 mm and a width of 100 mm,
After applying a resin flux used in soldering, hot air drying was performed at 120°C. Then the temperature is about 300
The slab was immersed for about 30 seconds in a molten Pb-Sn alloy at a temperature of 0.degree. C. so that the flux-treated surface was in contact with the slab, and solder plating was performed. The dipping time was adjusted so that the thickness of the solder plating was approximately 0.2 mm.
Thereafter, residual flux was removed with isopropyl alcohol, and then rolled into a lead alloy sheet with a thickness of 1 mm, which was expanded to form a lattice. The Sn concentration in the Pb-Sn alloy is 1, 1.5,
5, 10, 20, 40, 60, 80, 100%.

Furthermore, for comparison, a grid manufactured by the conventional method without applying the solder plating was prepared. This was made with a Sn concentration of 0.5%.

Using these prepared grids, we fabricated a 55D23 type automotive lead-acid battery specified by JIS standards and conducted a comparative test.

The amount of positive electrode active material per cell is approximately 500g.
The amount of negative electrode active material was 400 g, the specific gravity of the electrolyte was 1.26, and the amount was 800 g. 12V10W as a test to investigate charge recovery after over-discharging of these batteries.
The bulb was connected and discharged for 15 days at 40°C, then left open circuit for another 15 days. In this state, the battery was completely discharged, and the specific gravity of the electrolyte was approximately 1.02.

15V constant voltage (maximum current) at 20℃
25A) for 5 hours and examined the recovery performance.
FIG. 1 shows the relationship between charging time and changes in charging current. From this result, the Sn concentration was 0.5% without surface treatment, and the Sn concentration was 1.0% with surface treatment.
It can be seen that the recovery property is poor when the Sn content is 1.5% or more, but the recovery property after being left overdischarged is improved when the Sn content is 1.5% or more.

Next, the Sn concentration in the electrolyte was measured after the battery was left at 40° C. for 2 months. The results are shown in Figure 2.
This figure shows that the Sn concentration in the electrolyte increases rapidly when the Sn content in the alloy exceeds 20%, and increases even more rapidly when the Sn content exceeds 60%. The amount of self-discharge during storage and the decrease in the amount of electrolyte during the SAE life test also showed almost the same trends as this curve, and the Sn concentration was 20%.
It starts to get worse when it gets too far.

Therefore, from these two tests, the Sn concentration in the Pb-Sn alloy that improves the recovery performance after overdischarge without deteriorating the self-discharge and liquid reduction characteristics is 1.5 to 20.
It can be seen that a value between % is appropriate.

Considering the reason for this, Pb with Sn of about 20% or less
-Sn alloys are mostly α solid solutions in which Sn is dissolved in Pb, and have a metallic crystal structure in which Pb is interspersed in Sn. The rate of dissolution of tin in sulfuric acid in the α solid solution is extremely slow, and since the β solid solution is surrounded by the α solid solution, it is thought that it hardly dissolves. When the Sn concentration exceeds 20%,
A eutectic structure of the α solid solution and the β solid solution appears, and the above-mentioned crystal structure is mixed with the eutectic structure. Since the Sn concentration in the electrolyte increases from around this point, it is thought that the elution of Sn increases as the eutectic structure increases. When the Sn concentration exceeds about 60%, a mixture of eutectic structure and crystalline structure in which α solid solution is wrapped around β solid solution forms, and the dissolution rate further increases.

Considering this, the amount of Sn in the Pb-Sn alloy to be applied to the surface of the Pb-Ca-Sn alloy base material of the present invention is 1.5 to 1.
It can be seen that 20% is appropriate and that it is important that it exists as an alloy. For example, even if a metal mixture of the above ratio is applied to the surface, it cannot be expected to suppress elution.

In this example, a Pb-Sn alloy was attached to the surface of the base material, but it may also be a Pb-Ca-Sn alloy.
Strictly speaking, the alloy state in this case is different from that of a Pb-Sn alloy, but the above idea applies at around 0.05% Ca, which is commonly used.

Effects of the Invention According to the present invention, it is possible to provide a lead-acid battery with excellent charge recovery characteristics after being left over-discharged without impairing self-discharge and liquid-reducing characteristics.

[Brief explanation of drawings]

Figure 1 is a diagram showing the relationship between the tin content in the solder used to surface-treat the grid, charging time, and charging current;
FIG. 2 is a diagram showing the relationship between the tin content in the solder applied to the surface treatment of the grid and the amount of tin eluted into the electrolytic solution after a battery incorporating the same grid was left at 40°C for two months.

Claims (1)

[Scope of Claims] 1 At least one side of a base material made of a lead-tin-calcium alloy contains tin as a main alloy component and its content is
A lattice body for lead-acid batteries in which a lead-tin alloy layer or a lead-tin-calcium alloy layer of 1.5 to 20% by weight is integrated and developed into a mesh shape. 2 A lead-tin alloy layer or a lead-tin alloy layer containing tin as the main alloy component and containing 1.5 to 20% by weight on at least one side of a flat rolled material made of a lead-tin-calcium alloy.
A method for manufacturing a lattice for a lead-acid battery, which comprises integrating a tin-calcium alloy layer, rolling it to a predetermined thickness, and then subjecting it to an expanding process to form a mesh. 3. Production of a lattice for a lead-acid battery according to claim 2, wherein the flat rolled material and the lead-lead-calcium alloy layer integrated on at least one side thereof have a calcium content of 0.01 to 0.1% by weight. Law. 4. The method for producing a lead-acid battery grid according to claim 3, wherein the calcium content is 0.05% by weight.