JPH042059A - Clad type lead acid battery of sealed structure - Google Patents

Abstract

PURPOSE:To suppress costs and prolong the lifetime of a battery by using a pos. electrode grating consisting of an alloy of Pb-Sb series, and filling the space between a pos. electrode plate and a neg. electrode plate with fine powder of a mixture of silica and titanium dioxide in a specific mix proportion. CONSTITUTION:5-15% fine powder of titanium dioxide is mixed with fine powder of silica as major component having excellent liquid absorptiveness, and the space between a pos. electrode plate and a neg. electrode plate and their surrounding are filled with this mixture. Therein the fine powder of titanium dioxide adsorbs the Sb, which is thus hindered from movement from the pos. to neg. electrode. This eliminates drop of the hydrogen over voltage because of Sb, so that the water decomposition will not increase, and there is no fear of impairing such features as being free from maintenance and water refilling. This enables fabricating an excellent lead acid storage battery of sealed type at a low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to the improvement of a sealed lead-acid battery using a clad positive electrode plate.

Conventional technology and its issues In general, in batteries that use clad type plates for the positive electrode, the positive electrode active material is protected by a glass tube, etc., so there is less active material falling off even after repeated deep charging and discharging, and paste type plates are used. It has superior life performance and vibration resistance compared to batteries using

In recent years, there has been an increasing demand for lead-acid batteries to be maintenance-free, and clad batteries are also desired to be sealed. Conventionally, there are two types of sealed lead-acid batteries: retainer type and gel type. The retainer type inserts a matte separator (glass separator) made of fine glass fiber cod between the positive and negative electrode plates, which holds the sulfuric acid electrolyte necessary for charging and discharging and isolates the two electrodes. No maintenance, no leakage,
Taking advantage of its position-free characteristics, it has recently become widely used as a backup power source for portable devices and computers. However, there are many factors that increase the manufacturing cost of batteries, such as the expensive glass separator and the need to press the electrode plates strongly and increase the strength of the battery case. They have drawbacks such as inferior low rate discharge performance compared to liquid type batteries (also called liquid type batteries), which is an obstacle to the widespread use of this type of sealed battery.

On the other hand, although the gel type is cheaper than the retainer type, it has the disadvantage that its battery performance is inferior to the liquid type and retainer type.

In addition, most of both cage-type and gel-type sealed lead-acid batteries use a lead alloy that does not contain antimony for the lattice body. When a lead-antimony alloy is used in these batteries, antimony is eluted from the positive electrode grid during charging and discharging and precipitates on the negative electrode plate, reducing the hydrogen overvoltage, resulting in an increase in the amount of hydrogen generated due to water splitting. As a result, a fatal dry-up occurs in sealed lead-acid batteries, resulting in the end of their lifespan. For this reason, in cage-type and gel-type sealed lead-acid batteries, for example, a lead-calcium alloy is used as an antimony-free alloy. However, lead-
When calcium-based alloys are subjected to charge-discharge cycles that include deep discharge, a dense layer of lead sulfate, which is a nonconductor, forms at the lattice-active material interface during discharge, resulting in early capacity loss.
This has the disadvantage that the bond between the lead dioxide particles of the active material is weakened and the active material is likely to fall off. Furthermore, since lead-calcium alloys have lower strength than tin-antimony alloys, they also have the disadvantage that short circuits are more likely to occur due to lattice elongation.

On the other hand, in the case of antimony-based alloys, antimony makes the corrosion layer formed at the lattice-active material interface porous, and also strengthens the bonding force between lead dioxide particles, leading to early capacity loss and drop-off of the active material. Furthermore, short circuits due to lattice stretching are less likely to occur. For these reasons, the biggest challenge for current sealed lead-acid batteries has been to reduce costs and improve battery life performance at the same time.

Means for Solving the Problems In order to eliminate the drawbacks of the conventional sealed lead-acid batteries mentioned above, it is best to make it possible to use a lead-antimony based alloy for the positive electrode grid. However, for this purpose, preventing the movement of antimony from the positive electrode to the negative electrode is a major problem. As a result of repeated research, it was discovered that fine titanium dioxide powder adsorbs antimony.However, fine titanium dioxide powder has the disadvantage of poor absorption of dilute sulfuric acid. As a result of further investigation, we decided to use fine silica powder as the main ingredient, which has excellent liquid absorption properties.
By using titanium dioxide fine powder in combination, we were able to develop an inexpensive sealed lead-acid battery with excellent battery performance. The basic idea is to use a clad lead-acid battery that uses a positive electrode lattice made of a lead-antimony alloy, and uses a mixture of fine silica powder and fine titanium dioxide powder between and around the positive and negative plates. The purpose is to fill the

By using a lead-antimony alloy for the active positive electrode lattice, antimony makes the corrosion layer that forms at the positive electrode lattice-active material interface porous, which strengthens the bond between particles and prevents early capacity loss and drop-off of the active material. In addition, short circuits due to grid elongation can be reduced. Further, fine titanium dioxide powder placed in the gap between the positive electrode plate and the negative electrode plate adsorbs antimony and prevents antimony from moving from the positive electrode to the negative electrode. As a result, there is no reduction in hydrogen overvoltage due to antimony, so water decomposition does not increase, and the most important feature of sealed lead-acid batteries, which is no maintenance and no water replenishment, is maintained. Furthermore, since fine dioxide powder and fine silica powder are inexpensive industrial materials, and fine silica powder has an excellent ability to retain sulfuric acid, this mixed powder can be used as an electrolyte retainer using either a retainer type or a gel type. A sealed lead-acid battery that can replace the battery can be manufactured at low cost.

EXAMPLES Hereinafter, a sealed clad lead-acid battery according to the present invention will be explained using examples.

The battery was composed of three clad positive electrode plates with a height of 70 inches and four paste member electrode plates, and the gap between the positive and negative electrode plates was held by resin upper and lower joints. Note that a lead-antimony alloy was used for the core of the positive electrode plate, and a lead-calcium alloy was used for the lattice of the negative electrode plate.

This battery was filled with only silica fine powder and with varying mixing ratios of silica fine powder and rutile-type titanium dioxide fine powder having an average particle size of about 0.30 μm.

Next, add a sufficient amount of sulfuric acid electrolyte to charge and discharge the battery.
Closed clad lead-acid batteries A to E containing almost no free liquid were prepared by using fine silica powder or a mixed powder of fine silica powder and fine titanium dioxide powder and holding it between positive and negative electrode plates.

For comparison, a glass separator was inserted between the positive and negative electrode plates.
A sealed cage type battery F using a lead-antimony alloy for the positive electrode core metal and a cage type battery G using a lead-calcium alloy for the JE electrode core metal were also manufactured. In addition, batteries F and G
The same lead-calcium alloy as in batteries A to E was used for the grid of the negative electrode plate.

After conducting an initial capacity test (2HR), a charge/discharge cycle test (discharge depth 75%, charge amount 125%) was conducted to investigate each battery's performance and amount of liquid loss.

Here, the amount of liquid reduction is expressed in weight percent, with the value before the test being 0%. The results are shown in Table 1.

From Table 1, it can be seen that the life of Battery F was relatively long at F300~ compared to the life of Battery G, which used a lead-calcium alloy for the positive electrode core, but the amount of liquid loss was extremely large at 20%. -The drawback of using antimony-based alloys is that the amount of liquid loss due to hydrogen generation is large. On the other hand,
The so-called retainer type battery G had a very small amount of liquid loss of 3%, but had a short lifespan of 600 mA or more. The causes of this were that the positive electrode active material deteriorated easily because it did not contain antimony, and that the strength of lead-calcium alloys was lower than that of lead-antimony alloys, which caused the lattice to stretch and short circuits to occur. Ta.

Table 1 In contrast to these, battery A uses a bell-antimony alloy for the positive electrode core and fine silica powder for the electrolyte holder, or the product of the present invention uses a fine powder mixture of fine silica powder and fine titanium dioxide powder. Certain batteries B to D had a greater amount of fluid loss than the retainer type, but the results showed that their lifespans were significantly improved. Even Battery A, which uses only fine silica powder for the electrolyte holder, has a lifespan of 600 to 10% compared to conventional retainer type Battery G.
00~, which is a significant improvement or the amount of liquid reduction is large. However, batteries B to D, which are products of the present invention that are mainly composed of silica fine powder and added with titanium dioxide fine powder, have significantly improved life performance, although the amount of fluid lost is greater than that of the retainer type. Recognize. However, 20% titanium dioxide fine powder
In the mixed battery E, the amount of liquid loss was improved by the antimony absorption effect of titanium dioxide and was as low as 5%, but the life span was reduced to 950~, and the poor liquid absorption property of titanium dioxide became noticeable, and the silica From the results of 0 samples, which are estimated to have a lifespan lower than that of Battery A in which only powder was added, it can be seen that mixing 5 to 15% of titanium dioxide fine powder is most effective.

In the above example, the results were shown when titanium dioxide fine powder with a rutile crystal structure was used, but even when titanium dioxide fine powder with an anatase crystal structure was used, the amount of antimony adsorbed was lower than that of the rutile type. Although slightly less, almost the same life performance and liquid reduction characteristics as when using the rutile type were obtained. Because these are clad type positive electrode plates, some of the antimony that falls off from the positive electrode core metal is adsorbed by lead dioxide, an active material around the core metal, and the amount of antimony leached out of the positive electrode plate is reduced. It seems that even with the anatase type titanium dioxide fine powder, which has a slightly lower antimony adsorption amount, the battery performance did not change much.

Effects of the Invention As described above, the sealed clad lead-acid battery according to the present invention has a small amount of liquid loss, excellent life performance, and is inexpensive, and its industrial value is extremely large.

Claims (1)

[Claims] 1. In a clad lead-acid battery using a Pb-Sb alloy for the core, fine silica powder and fine titanium dioxide powder of 5 to 15% of the weight of the fine silica powder are added between and around the positive and negative plates. A sealed clad lead-acid battery characterized in that it is filled with a fine powder mixed with the above, and the mixed fine powder holds an electrolyte.