JP2001236962A - Lead battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a long-life lead battery controlling a local corrosion of a grill and for preventing both damage to the grating body and capacity reduction. SOLUTION: A positive electrode grill consisting of an alloy of lead, calcium, and tin contains indium. The alloy preferably contains 0.01 to 0.1 wt.% of calcium, 1.0 to 2.5 wt.% of tin, and a 0.01 to 0.5 wt.% of indium.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved lead-acid battery, and more particularly to a positive electrode grid.

[0002]

2. Description of the Related Art Conventionally, a lead-calcium-tin alloy has been used for a positive electrode grid of a lead storage battery. The alloy has a feature of solving the problem of maintenance-free, but has a disadvantage that the corrosion rate increases with an increase in the calcium content. Therefore, the upper limit of the calcium content is currently 0.1 wt%. Calcium increases the strength of the alloy, such as tensile strength and hardness, and improves workability.
It is desirable to add at least 01 wt%.

[0003] In order to solve the above-mentioned disadvantages of calcium, it has been proposed to increase the tin content in the lattice. This utilizes the effect that increasing the tin content in a lead-calcium-tin alloy reduces the corrosion rate.

[0004]

However, the lead-calcium-tin alloy has the property that corrosion proceeds selectively along the crystal grain boundaries. In particular, tin forms a structure in which the crystal grains are coarsened as the content increases. For this reason, the overall corrosion of the lattice body is suppressed, but the tendency of selective intergranular corrosion becomes strong, and as a result, there is a problem that the local capacity corrodes to lower the battery capacity and the life.

[0005] Therefore, there has been a long-awaited demand for the production of a lattice body which does not easily cause local corrosion.

An object of the present invention is to provide a long-life lead-acid battery that suppresses local corrosion of a grid body, prevents breakage of the grid body, and prevents a decrease in capacity.

[0007]

The lead storage battery of the present invention is characterized in that, in order to solve the above-mentioned problems, a positive electrode grid made of a lead-calcium-tin alloy contains indium. And the amount of calcium is 0.01-0.1 wt%, and the amount of tin is 1.0-2.5 wt%. The amount of indium is not particularly limited, but is 0.01 to 0.5 wt.
%, The effect is excellent.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the following examples.

First, the composition of each alloy was set to 0.1% for calcium.
The casting lattice body was manufactured by changing the content of 01 to 0.1 wt%, the content of tin to 1 to 2.5 wt%, and the content of indium to 0.01 to 0.5 wt%.

[0010] Next, the cast grid body thus obtained was tested at a test temperature of 40 ° C and a specific gravity of 1.25 sp. gr. Immersed in a sulfuric acid solution at a current density of 0.5 A / cm ² ,
The corrosion test was performed on the condition of day. The result is shown in FIG.

FIG. 1 is a diagram comparing the relationship between the tin content of a lead-calcium-tin alloy and the number of intergranular corrosion in the alloy containing no indium and the alloy containing 0.1 wt% indium. Here, the number of intergranular corrosion refers to the number at which intergranular corrosion has progressed for at least half of the thickness of the lattice. Since the change in the calcium content contributed to the hardness and did not affect the intergranular corrosion, the change was set at 0.09 wt%. On the other hand, if the tin content is increased to 2.5 wt% or more, a problem occurs in the production process, and the tin becomes unsuitable as a battery.

FIG. 1 shows that intergranular corrosion becomes remarkable at a tin content of 1 wt% or more, and increases with increasing tin content. Looking at the effect of indium content here, it can be seen that intergranular corrosion is suppressed regardless of the tin content.

Next, FIG. 2 shows the result of examining the number of intergranular corrosion by changing the indium content of the lead-Ca-Sn-In alloy. Here, for the master alloy to which indium is added, lead-0.09 wt% calcium-2 wt% tin was used as a typical composition in FIG. From FIG. 2, intergranular corrosion is significantly reduced until the indium content becomes 0.01 wt%,
Indium content from 0.01 wt% to 0.5 wt%
In the range, the effect was gradually decreased, and no more effect was observed at 0.5 wt% or more.

From the above results, it can be seen that a significant intergranular corrosion prevention effect can be obtained when the indium content is 0.01 wt% or more. However, when the content of indium is 0.1.
If the content exceeds 5 wt%, the effect of suppressing intergranular corrosion does not change, and if it exceeds 5 wt%, adverse effects such as promotion of self-discharge of the battery are caused.
To 0.5 wt%.

After the corrosion test, each lattice was cut and polished, and the corrosion state of the cross section 1 was observed. In addition, lead -0.09w
t% calcium-1wt% tin alloy and lead -0.09w
FIGS. 3 and 4 show the cross section 1 of the lattice body after the corrosion test of the t% calcium-1 wt% tin-0.1 wt% indium alloy, respectively. In FIG. 3, the blackened portion of the grain boundary 2 is a portion that has undergone corrosion, and grain boundary corrosion was observed in many portions of the grain boundary. On the other hand, in FIG. 4, it can be seen that the grain boundaries 2 are not blackened and are hardly corroded. That is, it can be seen that the alloy containing indium hardly causes intergranular corrosion as compared with the alloy not containing indium. this is,
Indium has high solubility in lead, is easy to diffuse,
Further, it is considered that this is because segregation of alloying elements was suppressed because of the amalgamated metal, and local corrosion including intergranular corrosion was suppressed.

Next, lead-0.09 wt% calcium-2.
0 wt% tin and lead-0.09 wt% calcium-2.0
wt% tin-0.5wt% indium alloy is used for the positive electrode grid, and lead-0.1wt
A conventional lead-acid battery A using a% calcium-0.5 wt% tin alloy and a lead-acid battery B of the present invention were produced. Using these batteries, an overcharge test was performed at a test temperature of 50 ° C. for 100 days. The result is shown in FIG.

FIG. 5 shows that the battery A of the present invention has a smaller decrease in capacity during the test period than the conventional battery B. Therefore, the use of the positive electrode grid body to which indium is added suppresses local corrosion of the grid body and suppresses a decrease in the capacity of the lead storage battery, so that a lead storage battery having excellent life performance can be provided.

If the content of tin is less than 1.0 wt%, the effect of reducing the corrosion rate described in the prior art is reduced, and if it exceeds 2.5 wt%, in the production process of the lead-acid battery, Since a large amount of tin oxide film is formed on the lattice body surface and it is difficult to bond the active material and the lattice body, the range is set to this range.

[0019]

As described above, according to the first aspect of the present invention, it is possible to provide a lead-acid battery having a long life by suppressing disconnection and a decrease in battery capacity due to corrosion of the positive electrode grid. According to the second aspect, the effect of the first aspect can be made remarkable.

[Brief description of the drawings]

FIG. 1 is a graph comparing tin content and intergranular corrosion number in a lattice of a Pb—Ca—Sn alloy and a lattice of a Pb—Ca—Sn—In alloy.

FIG. 2 is a diagram comparing the amount of indium added and the number of intergranular corrosion.

Fig. 3 Lead based on conventional product-0.09 wt% calcium-
It is a figure showing a section after a corrosion test of a 1 wt% tin alloy.

FIG. 4 Lead according to the present invention—0.09 wt% calcium—
It is a figure showing the section after the corrosion test of 1wt% tin-0.1wt% indium alloy.

FIG. 5 is a graph showing the results of an overcharge test of a product of the present invention and a conventional product.

Claims (2)

[Claims] 1. A lead-acid battery provided with a positive electrode grid made of a lead-calcium-tin alloy, wherein the grid is 0.01 to
A lead-acid battery comprising 0.1% by weight of calcium and 1.0 to 2.5% by weight of tin and indium. 2. The method according to claim 1, wherein said indium is 0.01 to 0.5 wt.
% Lead-acid battery.