JPH06295739A - Sealed lead-acid battery - Google Patents

Abstract

PURPOSE:To provide an inexpensive sealed lead-acid battery having excellent battery performance by using a positive electrode grid composed of lead- antimony type alloy, and using silica fine powder and microporous acidproof synthetic fiber. CONSTITUTION:Lead-antimony type allay is used in a positive electrode grid, and a corrosion layer created on an interface between the positive electrode grid and an active material is made porous, and bonding between particles is strengthened, and early capacity deterioration or falling of the active material can be prevented, and a short circuit caused by elongation of the grid can be also reduced. Silica fine powder arranged in a clearance between a positive electrode plate and a negative electrode plate and microporous acidproof synthetic fiber adsorb antimony, and prevents the movement of the antimony to a negative electrode from a positive electrode. As a result, since a drop in hydrogen overvoltage by the antimony is eliminated, water decomposition is not increased, so that characteristics such as maintenance free and water non- supply being the largest characteristic of a sealed lead-acid battery is not spoiled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved sealed lead acid battery.

[0002]

2. Description of the Related Art At present, there are two types of sealed lead-acid batteries, a retainer type and a gel type, in which a negative electrode absorbs oxygen gas generated during battery charging. The retainer type inserts a mat-shaped separator (glass separator) made of fine glass fibers between the positive electrode plate and the negative electrode plate, thereby holding the sulfuric acid electrolyte necessary for discharging and separating the two electrodes, In recent years, it has come to be widely used as a backup power source for portable devices and computers by taking advantage of features such as no maintenance, no leakage, and position-free.

On the other hand, on the other hand, there are many factors that increase the manufacturing cost of the battery, such as the expensive glass separator and the need to strongly press the electrode plate group, so that the manufacturing cost of the battery is high, and the fluid is excessive. There is a defect that the low rate discharge performance is inferior to a certain battery (hereinafter referred to as a liquid battery), which is an obstacle to the widespread use of this type of sealed battery. On the other hand, the gel type is less expensive than the retainer type, but has a drawback that the battery performance is inferior to the liquid type and the retainer type.

Most of the retainer and the gel-type sealed lead-acid battery use a lead alloy containing no antimony in the lattice. When a lead-antimony alloy is used in these batteries, antimony makes the corrosion layer generated at the lattice-active material interface porous, and in order to strengthen the bonding force between the lead dioxide particles, early capacity reduction and activity decrease. The substance does not fall off, and short-circuiting due to lattice expansion does not occur easily, but antimony elutes from the positive electrode lattice during charge and discharge and deposits on the negative electrode plate to reduce hydrogen overvoltage, so the amount of hydrogen generated by water decomposition is reduced. As a result, in a sealed lead-acid battery, fatal dry-up occurs and the battery life is reached.

For this reason, in the retainer and the gel type lead-acid battery, for example, a lead-calcium alloy is used as an alloy containing no antimony. However, when a lead-calcium alloy is subjected to a charge / discharge cycle including deep discharge, lead sulfate, which is a dense non-conductor, is generated at the lattice-active material interface at the time of discharge and the capacity is reduced early, or the active material is reduced. That is, the bond between the lead dioxide particles is weakened, and the active material easily falls off.

Further, the lead-calcium alloy is much softer than the lead-antimony alloy, and therefore has a drawback that a short circuit is apt to occur due to the elongation of the lattice. From these things, in the current sealed lead-acid battery, reducing the cost and improving the battery life performance have been the biggest problems.

[0007]

In order to eliminate the above-mentioned drawbacks of the conventional sealed lead-acid battery, it was considered that it is best to use a lead-antimony alloy in the positive electrode grid. However, preventing the transfer of antimony from the positive electrode to the negative electrode is a major problem for this purpose, but as a result of repeated research, it was found that the silica fine powder and the acid-resistant synthetic fiber having fine pores adsorb antimony. As a result, it has been possible to develop an inexpensive sealed lead acid battery having excellent battery performance by using fine silica powder and acid-resistant synthetic fiber having fine pores. The antimony adsorption power is stronger in the acid-resistant synthetic fiber having fine pores than in the silica fine powder.

A skeleton is made of a positive electrode grid made of a lead-antimony alloy, and silica fine powder and acid-resistant synthetic fiber having fine pores are filled and arranged in at least a gap between the positive electrode plate and the negative electrode plate. Then, the fine powder, the acid-resistant synthetic fiber, and the positive and negative electrode plates are impregnated and held with the sulfuric acid electrolytic solution in an amount necessary for charging and discharging.

Since the acid-resistant synthetic fiber having fine pores is not so well compatible with the electrolytic solution, it is preferably subjected to a hydrophilizing treatment such as sulfonation treatment or plasma treatment. Further, the acid-resistant synthetic fiber having fine pores is preferably used after being cut into fine pieces in order to facilitate filling.

[0010]

[Operation] By using a lead-antimony alloy for the positive electrode lattice, the corrosion layer generated by antimony at the positive electrode lattice-active material interface becomes porous, and the binding between particles is strengthened. Can be prevented from falling off, and short circuits due to lattice expansion can be reduced.

Further, the silica fine powder and the acid-resistant synthetic fiber having fine pores, which are arranged in the gap between the positive electrode plate and the negative electrode plate, adsorb antimony and prevent migration of antimony from the positive electrode to the negative electrode. As a result, the reduction of hydrogen overvoltage due to antimony is eliminated, so that water decomposition does not increase, and the main features of the sealed lead-acid battery, ie, no maintenance and no rehydration, are not impaired.

Further, since silica fine powder is a very inexpensive industrial material and has an excellent ability to retain sulfuric acid, it is possible to inexpensively manufacture a sealed lead-acid battery that replaces the retainer or gel type.

[0013]

EXAMPLES The present invention will be described below based on examples.
A battery was actually manufactured and tested.

For comparison, as shown in Table 1, a lead-antimony alloy and a lead-calcium alloy are used as the positive electrode grid alloy, and 10 to 10 primary particles are used as the electrolyte holder.
About 40 millimicron, a glass separator mixed with silica fine powder having a surface area of about 120 m ² / g and a conventional glass fiber having a diameter of about 0.8 micron, and a polyethylene fiber having a diameter of about 25 micron having hydrophilized fine pores are used. 5m
Those cut into m were used. The polyethylene fiber has fine pores of about 0.03 to 1 micron, and the porosity of the fiber is about 45% and the specific surface area is about 40.
It was m ² / g.

[0015]

[Table 1]

A lead-calcium alloy is used for the negative electrode grid. Standard positive and negative electrode active materials are used,
Dilute sulfuric acid with a specific gravity of 1.30 was used as the electrolyte, and the
A sealed lead-acid battery for an automobile having a capacity of Ah was assembled. A life test of JIS D-5301 was performed using these batteries, and the transition of discharge capacity and the amount of liquid reduction were examined. The discharge capacity is compared with the capacity before the test as 100%, and the liquid reduction amount is the liquid reduction amount in weight% with 0% before the test. The results are shown in Fig. 1.

No. The battery of No. 3 had the shortest life and had a large amount of liquid reduction. This is because antimony eluted from the positive electrode grid is deposited on the negative electrode plate to increase water decomposition and reduce the amount of the electrolytic solution. No. The batteries of Nos. 4 and 5 have a small amount of liquid reduction, but No. The life was shorter than the batteries 1 and 2. This is because deterioration of the positive electrode active material was likely to occur because it did not contain antimony, and the fact that the lead-calcium alloy was softer than the lead-antimony alloy and the lattice stretched to cause a short circuit. It is the cause.

No. No. 2 battery is No. The battery had a slightly shorter life than the No. 1 battery. This is because the fine silica powder has a weaker antimony adsorption force than the polyethylene fiber having fine pores.

On the other hand, in contrast to these, No. 1
In the battery using the lead-antimony alloy for the positive electrode grid and the fine silica powder and the polyethylene fibers having fine pores for the electrolyte holder, the result was that the number of lifespan was long and the amount of liquid reduction was very small. This is because deterioration of the positive electrode active material and elongation of the lattice were small because a lead-antimony alloy was used for the positive electrode lattice, and silica fine powder and polyethylene fibers having fine pores were used for the antimony positive electrode to the negative electrode. The reason is that the amount of liquid reduction has decreased due to the prevention of movement.

In this example, the silica fine powder has primary particles of 10 to 40 mm and a surface area of about 120 m.
^Although the silica fine powder having a surface area of 20 m ² / g or more was used, the same effect can be obtained.

Further, this time, the ratio of the acid-resistant synthetic fiber having fine pores to the silica fine powder is set to 20%.
The effect was remarkable in the range of 70%.

Further, the same effect as in the present embodiment can be obtained for a clad type sealed lead-acid battery using a lead-antimony alloy for the positive electrode grid, the above silica fine powder and an acid-resistant synthetic fiber having fine pores for the electrolyte holder. That is, the amount of reduced liquid is small and a long life can be expected.

[0023]

As is apparent from the above-described embodiments, the sealed lead-acid battery according to the present invention uses the positive electrode grid made of the lead-antimony alloy and has the silica fine powder in at least the gap between the positive electrode plate and the negative electrode plate. And acid-resistant synthetic fibers having fine pores are filled and arranged, and the fine powder, the acid-resistant synthetic fibers and the positive and negative electrode plates are impregnated and held with the sulfuric acid electrolytic solution in an amount necessary for charging and discharging, which is a conventional hermetic seal. The disadvantages of the lead-acid battery can be overcome and its industrial value is enormous.

[Brief description of drawings]

FIG. 1 is a diagram showing a change in capacity and a liquid reduction amount during a cycle life test.

Claims (1)

[Claims] 1. A sealed lead acid battery in which oxygen gas generated during charging of the battery is absorbed by a negative electrode, a positive electrode grid made of a lead-antimony alloy is used, and silica is provided at least in a gap between the positive electrode plate and the negative electrode plate. Fine powder and acid-resistant synthetic fiber having micropore fibers were filled and placed, and the sulfuric acid electrolytic solution in an amount necessary for charging and discharging was impregnated and held in the fine powder, acid-resistant synthetic fiber and positive and negative electrode plates. Characteristic sealed lead acid battery.