JPH04132167A - 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 the Invention The present invention relates to grid alloys and separators for lead-acid batteries.

BACKGROUND OF THE INVENTION Lead alloys containing antimony have good castability and increase the strength of the lattice, and have excellent properties such as recovery after over-discharging and long-term storage. On the other hand, there are problems in that self-discharge increases and the amount of electrolyte decreases while the battery is in use.

This is because the antimony used in the positive electrode is eluted into the electrolytic solution and deposited on the surface of the negative electrode, forming a local battery of lead and antimony in that area and promoting self-discharge. On the other hand, lead-calcium alloy lattices reduce the loss of electrolyte during battery use and eliminate the need for water replenishment, so there has recently been an increase in the number of maintenance-free batteries using them.

Problems to be Solved by the Invention However, when a lead-calcium alloy lattice is used for the positive electrode, abnormal over-discharge occurs, and if left as is for a long period of time, the interface between the positive electrode lattice and the active material Since a passive film with high resistance is formed on the battery, the charging acceptance performance deteriorates and charging may not be possible depending on the actual usage conditions.

Therefore, the positive electrode plate is made of a so-called low-antimony lead alloy, which has a lower antimony content of 4% by weight or less than before, and although problems remain in terms of castability and strength, we have focused on suppressing self-discharge and making it maintenance-free. Ta.

On the other hand, the negative electrode does not have any problems with charge recovery after overdischarge, and by expanding the lead-calcium alloy and using a lattice made of punched plates, it eliminates the use of antimony and reduces self-discharge. At the same time, hybrid type batteries, which raise the hydrogen overvoltage to cause electrolysis of the electrolyte during charging, came to be used depending on each application. For this type of battery, a paper-made type was used in which a glass mat was pasted together as a separator, and after each electrode plate was created, they were combined to form a group of electrode plates, but there was a limit to the ability to reduce the diameter of the fibers used in paper-making. However, the pore size used as a separator was adjusted, and silicon dioxide was mixed in to make the pore shape more complex.
This was insufficient to suppress the migration of antimony from the positive electrode to the negative electrode.

Means for Solving the Problems The present invention provides a positive electrode plate using a lead-antimony alloy grid having an antimony content of 4% by weight or less, a negative electrode plate using a lead-calcium alloy grid, and a thermoplastic synthetic resin. The present invention provides a lead-acid battery that reduces self-discharge by configuring the electrode plate group with separators consisting of the following.

By using a positive electrode plate made of a lead-antimony alloy lattice with an antimony content of 4% by weight or less, a negative electrode plate made of a lead-calcium alloy lattice, and a separator made of thermoplastic synthetic resin, antimony can be removed. This reduces elution, captures antimony eluted into the electrolyte with a separator, suppresses its migration to the negative electrode, and reduces self-discharge.

Example The present invention will be explained in detail below.

For the positive electrode plate, a lattice body is prepared which is cast using a lead-antimony alloy consisting of 4% by weight of antimony, 0.2% by weight of arsenic, and the balance being lead. On the other hand, the weight of the active material is 0.0
A paste was prepared by cutting polyester fibers into approximately 2% length and adding them during mixing with dilute sulfuric acid and active material. After this paste was filled into the grid, it was aged and dried to produce an unformed positive electrode plate having a height of 120 nn, a width of 108 cm, and a thickness of 1.8 cm.

The negative electrode plate contains 0.0 calcium as a lead-calcium alloy.
A slab containing 8% by weight of tin, 0.6% by weight of tin, and the balance lead is cold-rolled with a roll to create a thin plate with a thickness of 0.8 spindle, and this is expanded into a net shape to create a lattice body. do. Next, berylum sulfate with a particle size of 3μ or less is added to the lead oxide along with a lignin system so that the amount of barium present in the active material is 1% by weight, and the resulting paste is mixed with dilute sulfuric acid. This lattice was filled, a sheet mainly composed of pulp was attached to one or both sides, and then aged and dried to produce an unformed negative electrode plate with a height of 120 mm, a width of 108 mm, and a thickness of 1.5 mm.

The separator is made of a material mainly composed of polyethylene as a thermoplastic resin, with a sheet made of pores formed by solvent extraction of a mixture of the material, and a sheet made mainly of pulp whose surface is protected with phenol resin and silicon dioxide mixed therein. The paper-making type reinforcing fiber sheet bound together with a height of 12
Cut to 4mm+, width 115m, thickness 0.6mm,
A glass mat of the same size and a thickness of 1.2 cm was attached to this. Figure 1 shows the results of comparing the pore size distributions of both the polyethylene sheet and the reinforced fiber sheet. Conventional paper-making type reinforced fiber sheets ■ have pore diameters distributed over a wide range of 1 μ or less with a maximum pore diameter of 20 μ, whereas sheets ■ made mainly of polyethylene have a maximum pore diameter of 1 μ.
It is mostly concentrated in the vicinity, indicating that the pore diameter is uniformly small throughout.

A group of electrode plates is created by combining these electrode plates and each separator, and after injecting an electrolyte solution containing 5 g/l of sodium sulfate, the amount of positive electrode active material per cell is 500 g by forming the battery into a container. The negative electrode active material was adjusted to yield a 400 g battery. Assuming that the specific gravity of the electrolyte is 1.26, J
Twelve lead-acid automotive batteries of the 55D23 type specified in the IS standard were prepared, and a comparative test of self-discharge was conducted.

The results are shown in the table below.

IOA discharge test results depending on the material of the separator, both initially and after being left in a 40℃ atmosphere for 3 months.Measure the capacity when these batteries were first kept at 20℃ and then discharged to 1.7V/cell at a constant current of 8A. The battery was left in an atmosphere at 40° C. for 3 months, and then discharged to 1.7 V/cell at a constant current of 8 A to measure the capacity. The results showed that the polyethylene-based sheet retained 63.5% of its initial capacity, but the conventional paper-making type reinforced fiber sheet had a high self-discharge rate of 49.8%. did.

This is due to the fact that the pores in the separator are concentrated in a small area around 1μ, and at the same time, the pores penetrating the separator have a complex shape, resulting in the transfer of antimony ions from the positive electrode grid to the negative electrode plate. This is because migration is suppressed. However, if the pore size is made too small, the absolute volume of the pore decreases and the electrical resistance increases, resulting in a decrease in voltage characteristics when discharging at a large current, such as in the case of automobile batteries.
This is disadvantageous in obtaining large output.

Here, we selected polyethylene as the synthetic resin that forms the main body of the separator, but similar results can be obtained using polypropylene, copolymers thereof, vinyl halides, and vinylidene polymers, which can be made into minute pores by solvent extraction. be able to.

Further, although a flat separator was used in the embodiment, by making the separator into a bag shape and storing the positive electrode plate therein, it is possible to prevent antimony from migrating from the side, and good results can be obtained.

Effects of the Invention As described above, the present invention provides a positive electrode plate using a lead-antimony alloy lattice with an antimony content of 4% by weight or less, a negative electrode plate using a lead-calcium alloy lattice, and a separator made of a thermoplastic synthetic resin. By using the electrode plate group configured by the above, it is possible to provide a lead-acid battery with excellent self-discharge characteristics.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the pore size distribution of the separator in the present invention.

Claims (1)

[Claims] An electrode plate composed of a positive electrode plate using a lead-antimony alloy lattice with an antimony content of 4% by weight or less, a negative electrode plate using a lead-calcium alloy lattice, and a separator made of thermoplastic synthetic resin. Lead-acid battery using groups.