JPH01149368A - Lead-acid battery - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a lead-acid battery using a non-antimony alloy in the positive and negative electrode grids, and particularly to improving its life characteristics at high temperatures.

Conventional technology Conventionally, a lead-antimony alloy has been used as the lattice alloy for both the positive and negative electrodes of lead-acid batteries (hereinafter referred to as sb).
(referred to as a lattice battery). However, this type of battery is 1)
, significant self-discharge, 2).

There is a problem that there is a lot of liquid loss, and in order to improve this problem, batteries using a non-antimony alloy for the positive electrode grid and a non-antimony alloy for the negative electrode grid have recently been put into practical use. A typical example of this non-antimony alloy is a lead-calcium alloy (hereinafter referred to as a Ca lattice battery).
These two problems have been greatly improved, and the battery is called a maintenance-free battery.

Problems to be Solved by the Invention When a battery is used at high temperatures, the life mode is corrosion of the positive electrode grid. In other words, the oxygen overvoltage and hydrogen overvoltage decrease at high temperatures, so when charging at constant voltage, the overcharging current becomes several times that at room temperature, and the corrosion rate of the positive electrode grid increases significantly. Bring the battery to premature end of life.

Considering this point of view, Ca lattice batteries, which have been increasingly used in recent years, have a smaller overcharge current than conventional SB lattice batteries, so the corrosion rate of the positive electrode lattice is lower, and a longer life can be expected.

However, in reality, there is almost no difference between the two.

The reason for this is that in the case of a Ca lattice battery, in addition to the life mode of corrosion of the positive electrode lattice, there is also a life mode of performance deterioration due to inactivation of the positive electrode active material. That is, since the Ca lattice battery does not contain sb in its battery system, the hydrogen generation overvoltage at the negative electrode is high, and when the charging of the negative electrode active material is completed, the negative electrode potential shifts to a less noble potential compared to the conventional sb lattice battery.

Therefore, when charging at a constant voltage, the potential is not high enough to completely charge the positive electrode active material, and some of the positive electrode active material remains as lead sulfate in the discharged state, and this lead sulfate When exposed to high temperatures, it is inactivated and causes the so-called sulfation phenomenon of the positive electrode active material.

For the above reasons, the life characteristics of Ca lattice batteries at high temperatures were almost the same as those of SB lattice batteries.

As described above, the present invention aims to prevent sulfation of the positive electrode active material and provide a battery with a longer life by improving the charge acceptance of the positive electrode at high temperatures in a battery that does not contain sb in the lattice alloy system. With the goal.

Means for Solving the Problems As a specific means, the present invention uses lead powder containing red lead, water, and sulfuric acid as the main ingredients, and a paste made by kneading these together is used as the positive electrode active material. The content of red lead is 10 to 50 wt% of the total amount of lead powder.

Function As described above, by adding red lead to the positive electrode active material paste, it is possible to extend the life of the Ca lattice battery at high temperatures.

This effect is due to the fact that the inclusion of red lead increases the porosity of the positive electrode active material and increases the roughness factor, thereby improving the charge acceptance of the positive electrode. It is possible to obtain a paste with a certain degree of porosity by controlling the amount of water and sulfuric acid added in the process of making a paste using conventional lead powder containing Lissage, which does not contain lead. If a seed paste is used, the lifespan at room temperature will be significantly reduced.

As the content of red lead increases, charge acceptance improves. For example, the chargeability and acceptability of the positive electrode active material are improved even when the amount of addition is large, and becomes noticeable when the amount is 100% or more.

Conversely, when the red lead content exceeds 50 wt%, the life at room temperature decreases. Therefore, an appropriate content of red lead is 1O-6oW@, and within this range, it is possible to improve the lifespan at high temperatures without deteriorating the lifespan characteristics at room temperature.

When a non-antimony-based alloy is used for the grid, there is an expanded method of constructing the grid, but since the grooves of the expanded grid are generally larger than those of the cast grid, red lead is added to increase charge acceptance. This is very effective.

Example The present invention will be explained in detail below with reference to Examples.

(Example 1) First, a positive electrode plate was prototyped using a paste containing 0 to 80 wt% of red lead, and after completion of chemical formation, charging and discharging were repeated at 80°C. The content of lead sulfate was investigated.

The cell was prototyped with a configuration of one positive electrode/two negative electrodes.

This prototype cell is designated as A. The battery discharges at 6A for 14 minutes, and charges at a constant voltage of 2.5V/+J at 5A.
maximum), 10 minutes. This charging and discharging was repeated 20oO times, and after the test, lead sulfate in the positive electrode active material was quantitatively analyzed. The results are shown in FIG.

As is clear from Figure 1, as the content of red lead increases, the amount of lead sulfate after charge/discharge cycles tends to decrease, indicating that charge acceptance is improved. .

In addition, when we observed the size of lead sulfate crystals in the quantitative analysis using an electron microscope, we found that some lead sulfate crystals in samples that did not contain any lead red were over 100 pm, but the lead sulfate crystal size was 50 pm or more.
Maximum 30μ for t% sample! This fact indicates that the addition of red lead suppresses the inactivation of the positive electrode active material.

(Example 2) A positive electrode plate was prototyped using a paste containing O.~80 wt% red lead, a battery was assembled, and a life test was conducted at ao'c (high temperature) and 26°C (room temperature). This battery is called B.

Fig. 2 shows the test results at 80°C, and Fig. 3 shows the test results at 26°C.

As shown in FIG. 2, the life characteristics at 80° C. increase when the red lead content is in the range of 0 to 20 wt %, and remain almost constant above that. On the other hand, the life characteristics at 26℃ are 0 to 50wt.
% range, it is almost constant, but it decreases significantly in the larger range.

In addition, in this life test, by using lead powder containing Lissage as the main component without adding any red lead, and by selecting the amounts of water and sulfuric acid added, a product with the same apparent specific gravity as the red lead content of 20 wt% was obtained. A prototype paste was made and a similar life test was conducted.

This battery is called C.

Although some effect was seen in the life characteristics at 80°C, 2) a significant decrease was seen at 5°C.

As mentioned above, when the red lead content was 10 to 50 wt%, only the high temperature life characteristics could be improved without deteriorating the life performance at room temperature.

Effects of the Invention As described above, the present invention improves the high-temperature life characteristics of a battery using a non-antimony-based lattice.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the results of quantitative analysis of lead sulfate in the positive electrode active material after repeated charging and discharging of a battery equipped with a positive electrode plate prototyped based on the present invention, and Figures 2 and 3 are in accordance with the present invention. FIG. 2 is a diagram showing the life ratio at 80° C. and 26° C. of a battery prototype produced based on the invention. A: Prototype cell of the present invention, B: Prototype battery of the present invention, C: Conventional battery without the addition of red lead. Name of agent: Patent attorney Satoshi Nakao, and one other person Figure 1 Amount of joint of fI+ (%) Figure 2 Amount of apricot shavings of lead red (%)

Claims (3)

[Claims] (1) A lead-acid battery characterized in that a non-antimony-based lead alloy is used for the positive electrode grid and the negative electrode grid, and a paste made by kneading lead powder containing red lead, sulfuric acid, and water as the main components is used as the positive electrode active material. (2) The lead-acid battery according to claim 1, wherein the content of red lead is 10 to 50 wt% of the total amount of lead powder. (3) The lead-acid battery according to claim 1, wherein the positive electrode grid is an expanded grid obtained by lath processing a lead sheet.