JPH11191409A - Sealed lead-acid battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep high rate discharge characteristic equal to or more than the conventional battery and at the same time improve the trickle lifetime. SOLUTION: By limiting the surface area per 20 hour rate capacity of a negative electrode plate to be 24-30 cm<2> /Ah, the trickle lifetime is improved, even if the conventional positive electrode grid alloy is used, and high rate discharge capacity is kept in the same level as the conventional battery. By limiting the surface area of the negative electrode, an oxygen gas absorbing reaction velocity is suppressed, and the amount of lead sulfate in the negative electrode produced by the oxygen gas absorbing reaction is reduced. Reduction current based on the reduction of lead sulfate in trickle charge is decreased, and trickle current can be made to decrease. As a result, the trickle lifetime is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a communication device and a communication device.
The present invention relates to a sealed lead-acid battery used for an emergency backup power source such as a PS.

[0002]

2. Description of the Related Art There are several factors for the life of a conventional sealed lead-acid battery. The main factors are deterioration of a positive electrode plate, in particular, a reduction in active material holding power and a decrease in conductivity due to corrosion of a positive electrode grid. Things. This is a phenomenon that cannot be avoided in all lead-acid batteries, not limited to sealed lead-acid batteries. Until now, studies on corrosion-resistant lattice alloys and the like have been made, but are not yet sufficient. Therefore, the market demands a further increase in the service life, but it has been difficult to increase the service life using the conventional technology.

[0003]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to improve the trickle life while maintaining a discharge capacity equal to or higher than that of a conventional battery.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention comprises a positive electrode plate, a negative electrode plate, a separator serving also as an electrolyte impregnating material, a dilute sulfuric acid electrolyte and a synthetic resin battery case. In a sealed lead-acid battery in which the amount of the electrolyte is limited to the extent that almost no electrolyte is present, the surface area of the negative electrode plate per 20 hour rate discharge capacity is 24 to 30 cm ² / Ah
It is what it was.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A sealed lead-acid battery has conventionally used a grid manufactured by a casting method. This casting grid is obtained by injecting a molten lead alloy into a mold and solidifying it, and is generally similar to a shoji grid. Therefore, in a sealed lead-acid battery in which the electrode group is compressed and inserted into a battery case, particularly in the case of trickle use in which charging is performed continuously for a long time, the grid of the positive electrode plate is corroded during charging, thereby causing the positive electrode plate to move up and down. And tended to expand left and right, and depending on the conditions, the battery case could be damaged. During trickle charging, the positive electrode plate is constantly oxidized. Part of the charging current at this time is used for self-discharge charging, part of it is used for electrolysis of water in the electrolyte, and another part is used for oxidation (corrosion) of the positive electrode grid. Have been. Therefore, the positive grid is always corroded by oxidation during charging, and the grid expands due to volume expansion at the time of the corrosion, and its life is extended, and in some cases, the battery case is damaged. This trickle current is most preferably basically used only for charging the self-discharged component, but it is difficult to realize with the current technology. The amount of self-discharge of a sealed lead-acid battery is about 0.15% / day at 25 ° C.
(100%) / 24h = 0.00008 CA. For example, a battery with a rated capacity of 7.2 Ah has a current of 0.58 mA. In contrast, the trickle current of the current sealed lead-acid battery is about 36 mA, which is equivalent to 0.005 CA, which is much larger than the current required to supplement self-discharge.

In view of the above background, the present invention seeks to improve the trickle life by keeping the discharge capacity as high as that of a conventional battery, reducing the trickle current as much as possible, and suppressing the corrosion of the positive electrode grid. Things. The trickle current is affected by the magnitude of the self-discharge, the concentration of the electrolyte, impurities in the electrolyte, and the like, and also by the configuration conditions of the battery. It is also affected by the rate of the reaction that causes the negative electrode to absorb oxygen gas generated from the positive electrode plate during charging, which is a phenomenon unique to sealed lead-acid batteries. When the negative electrode plate absorbs oxygen gas, the metal lead becomes lead sulfate, and the potential of the negative electrode active material moves in a noble direction. If the potential of the negative electrode becomes noble, the voltage difference between the charger and the battery in a sealed lead-acid battery charged at a constant voltage increases, and the charging current increases. That is, the trickle current increases. The oxygen gas absorption rate is affected by the surface area of the negative electrode active material, the state of distribution of the electrolytic solution, and the moving speed of oxygen gas in the battery. The distribution of the electrolyte affects the discharge reaction or life of the battery, and the movement speed of the oxygen gas is related to the amount of the electrolyte in the battery and the physical properties of the separator. I can't change. Therefore, the oxygen gas absorption rate can be reduced by reducing the surface area of the negative electrode active material. Increasing the surface area of the negative electrode increases the oxygen gas absorption rate, so that the potential of the negative electrode plate becomes noble and the trickle charge current increases. On the other hand, when the surface area of the negative electrode is reduced, the potential is hardly noble, and the trickle current is reduced. Therefore, the trickle current can be reduced as much as possible by reducing the negative electrode surface area of the battery, in other words, the negative electrode surface area per discharge capacity. Thereby, corrosion of the positive electrode grid is suppressed, and the trickle life can be improved.

However, since the discharge capacity of the battery depends more on the negative electrode surface area than on the negative electrode active material amount, especially at the time of large current discharge, if the surface area is made too small, the discharge capacity at the time of large current discharge will decrease. . Therefore, a surface area above a certain value is required.

For the above reasons, the present invention specifies a configuration for achieving both the trickle life and the discharge capacity. Based on the results of many tests, the present invention pertains to a sealed lead-acid battery having a discharge capacity per 1 Ah at a 20-hour rate discharge. The negative electrode plate had a surface area (surface area of the front and back surfaces excluding the thickness of the electrode plate) of 24 to 30 cm ² .

[0009]

An embodiment of the present invention will be described below.
The dimensions are 20 mm per sheet when a sealed lead-acid battery is made of a positive electrode plate 65 mm long, 41.5 mm wide and 3.0 mm thick.
The time rate discharge capacity uses a positive electrode plate of 2.0 Ah, and the negative electrode plate has a length of 65 mm and a width of 44.0, 41.5, 38.5, 3.
Using grids of 3.3, 28.2, 23.1 and 17.9 mm, the grid was filled with the same amount of paste as was filled to a width of 41.5 mm. A battery having five positive electrode plates and six negative electrode plates was formed from the electrode plates via a retainer made of a glass fiber mat. The discharge capacity at a 20 hour rate of this battery is about 10 Ah. The conventional battery has a width of 4
1.5 mm.

[0010] These batteries are manufactured by a usual method, and
The time rate discharge capacity and the discharge capacity at 3 CA were measured. Also,
Trickle charging was performed at a constant voltage of 2.28 V per cell in an atmosphere of 40 ° C., and a charging current value and a trickle life after three months of charging were measured. The battery was discharged at a current of 3 CA every three months, and the life was determined when the discharge time became 1/2 of the initial discharge time. Table 1 shows an example of the discharge capacity measurement results.

[0011]

[Table 1]

FIG. 1 shows the relationship between the trickle current value, the trickle life, the discharge capacity during 3CA discharge, and the negative electrode plate surface area / 20 hour rate capacity.

From these results, the influence of (negative electrode plate surface area / 20 hour rate capacity) is shown below in comparison with Battery B of the conventional configuration.

First, the discharge capacity at the time of 3CA discharge decreases when its value is less than 24 cm ² / Ah. The trickle charge current sharply increases when its value exceeds 30 cm ² / Ah. Along with this, the trickle life tends to sharply decrease.

In summary, the initial discharge capacity, especially 3
In order to make the discharge capacity at the time of large current discharge of about CA almost the same as that of the conventional battery and to improve the trickle life, the surface area per 20 hour rate discharge capacity (excluding the thickness of the electrode plate, The area can be attained by using a negative electrode plate having an area of 24 to 30 cm ² / Ah.

This is because the trickle current is reduced by reducing the reduction current of lead sulfate generated by the oxygen absorption reaction on the negative electrode plate, which forms part of the trickle current, by limiting the oxygen absorption reaction rate. It is considered that the effect of lowering the trickle current suppressed corrosion in the positive electrode grid, thereby improving the trickle life.

[0017]

According to the above results, the positive electrode plate, the negative electrode plate, the separator also serving as the electrolyte impregnating material, the dilute sulfuric acid electrolytic solution and the synthetic resin container were inserted into the container in a compressed state. By using a negative electrode plate having an apparent surface area of 24 to 30 cm ² / Ah per 20 hour rate discharge capacity of a sealed lead-acid battery with a limited amount of electrolyte, the high rate discharge capacity is equivalent to that of a conventional battery. After that, the trickle current during trickle charge is further suppressed, and as a result, the trickle life is greatly improved, and this industrial value is extremely large.

[Brief description of the drawings]

FIG. 1 shows a sealed lead-acid battery 2 according to an embodiment of the present invention.
The figure which shows the relationship between the negative electrode surface area per 0 hour rate capacity, 3CA discharge capacity, trickle charge current at trickle charge, and trickle life.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshihiro Inoue 1006 Kazuma Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] 1. A hermetic seal comprising a positive electrode plate, a negative electrode plate, a separator also serving as an electrolyte impregnating material, a dilute sulfuric acid electrolyte and a synthetic resin battery case, wherein the amount of the electrolyte is limited to such an extent that free electrolyte hardly exists. In the lead-acid battery, the surface area of the negative electrode plate per 20 hour rate discharge capacity is 24 to 30 cm ² / Ah
A sealed lead-acid battery characterized by the following.