JPS63250066A - Hermetically sealed lead-acid battery - Google Patents

Abstract

PURPOSE:To improve hermetically sealed reaction efficiency, discharging capacity and deep discharging cycle lifetime by composing a group of plates with positive plates, negative plates and specific separators, employing specific dilute sulfuric acid and providing spaces in the partial side areas of the group of plates. CONSTITUTION:A group of plates is composed of positive plates 1, negative plates 2 and separators 3 made of flexible flat perforated plates mainly including glass fibers with average diameter of 5-25 micron and installed in a battery jar 6 provided with a valve 7. Respective spaces 8 are formed between each of the separators 3 on both sides and each inner wall of the battery jar 6 to serve as a passage for fuel oxygen. Gelatinous dilute sulfuric acid electrolyte 9 including 3-7 percentage by weight of silica grain is provided in the holes of the separator 3 and partial areas of the spaces 8. Therefore, the quantity of the electrolyte staying in the separator becomes large to put the space reaction efficiency to be enhanced and also sulfuric acid diffuses from soft gelatinous electrolyte to prevent the liquid in the group of plates from being neutralized. And also, generation of difference of density between upper and lower parts of electrolyte by repeat of deep discharging can be prevented by the difference in steam pressure to improve hermetically sealed reaction efficiency, discharging capacity and deep discharging cycle lifetime.

Description

[Detailed description of the invention] Industrial applications The present invention relates to improvements in sealed lead-acid batteries.

Conventional technology and its problems Sealed lead-acid batteries that react oxygen gas with a negative electrode plate are of the gel type using a gel electrolyte containing 7 to 15 percent by weight of silica, and the thin battery with a diameter of about 20 microns or less. The common type is the Ridena type, which uses mat-like leverage made of glass fiber. The materials placed between the positive and negative plates of a gel battery include a hard conventional gel with a silica content of 7 to 15 percent by weight, a corrugated microporous separator, a glass mat approximately 20 microns in diameter, and a corrugated porous plate. Non-woven fabrics and frames for maintaining spacing are in practical use1: Soft gel with a sillage capacity of Q and 5 to 7 weight percent is mainly made of thin glass fibers with an average diameter of several microns or less. Pine 1 rib-like perforated plates have been put into practical use.

In the former case, the gel-like electrolyte itself prevents the active material from falling off, and also has the function of a lever that isolates the two electrode plates by suppressing the growth of the di-dried lead. This is b for distributing the structures.

In addition, since the latter (U) porous plate itself functions as a separator, a soft gel electrolyte with a small amount of silica is used.

Sealed lead-acid batteries cannot be replenished with water due to their structural characteristics, so oxygen gas generated from the positive electrode plate moves to the negative electrode plate, contacts the negative electrode plate, and reacts, resulting in an excellent sealing reaction efficiency. Since it is often used in discharge cycles, it is desirable that it can withstand this and have a long life.Furthermore, it is desirable that it has a large capacity under the discharge conditions according to the load.
You have to pull it. However, in a battery using a hard gel electrolyte containing 7 to 15 percent by weight of silica, the sealing reaction efficiency is good, but the discharge capacity and deep cycle life are somewhat inferior. On the other hand, in batteries using gel with a small amount of silica, the sealing reaction efficiency is poor, and the electrolyte water] (1
There is a problem in that the concentration of sulfuric acid increases due to the loss of sulfuric acid and the electrode plate deteriorates. In the former case, this is due to the slow movement of ions in the gel part and the stratification phenomenon in which the concentration of FA acid at the bottom of the electrode plate increases.In the latter case, the dense leverator has a gel-like structure. This is because the No. 12 solution is retained and inhibits the movement of oxygen gas.

Means for Solving the Problems The present invention comprises an electrode plate group consisting of a positive electrode plate, a negative electrode plate, and a separator consisting of a flexible flat porous plate mainly made of glass fiber with an average diameter of 5 to 25 microns. The electrode plate group is housed in a battery case with a valve in a strongly compressed state, and at least 3 to 7 weight percent of silica particles are present in the holes of the separator and a part of the sides of the electrode plate group. A gel-like dilute sulfuric acid electrolyte is present, and a void is provided in a portion of the side of the horizontal plate group.
In addition, the fibers constituting the separator should have a non-woven ffi-like structure that does not have a fixed orientation in a plane, or the cathode active material should be mixed in the order of the strength of the dilute sulfuric acid electrolyte, starting from the one with the highest liquid retention capacity. The negative electrode active material and the separator should be placed in this order, or the electrode plate group should be prepared using a gel-like dilute sulfuric acid electrolyte, which is a mixture of colloidal silica and dilute sulfuric acid, in which fine silica particles are suspended in water. The present invention aims to provide a sealed lead-acid battery that solves the problems of conventional batteries by injecting the compound into a battery containing the compound and gelling it.

Example The present invention will be explained with reference to FIG. 1, which shows an embodiment thereof.

In the figure, 1 is a positive electrode plate, 2 is a negative electrode plate, and the lattice used in these plates does not substantially contain an element that lowers the hydrogen overvoltage of the negative electrode plate, that is, ambumon. 3 is a separator, which is a flexible flat porous body made by bonding glass fibers with an average diameter of 5 to 25 microns with a small amount of thermoplastic plastin fibers or a plastic bonding agent. 4
is a positive electrode conductor, 5 is a negative electrode conductor, 6 is a battery container whose lid is equipped with a valve 7, and consists of a group of electrode plates 1, 2 and 3, and an electrolyte held therein. It houses the power generation element. The electrolytic solution contains 3 to 7 weight percent of silica fine particles having an average diameter of 20 mm or less.

Since the pore size of the active material of the electrode plate is smaller than that of the separator, the silica fine particles are present in a high concentration in the separator and in a low concentration in the active material due to a filtration phenomenon. 8 is the electrode plate 8
A gap exists in a part of the side of Y and is a passage for gas space. Reference numeral 9 denotes an electrolytic solution present in a part of the electrode plate group, which is in contact with the electrode plate group, and has almost the same silica mrli as the electrolytic solution impregnated into the separator. .

The electrode plate group consisting of 1.2 and 3 is strongly pressed by the inner wall of the battery case. That is, the separator 3 strongly presses the positive electrode plate 1 and the negative electrode plate 2.

The separator 3 is preferably a non-woven fabric made by dissolving glass fibers with a length of several millimeters to more than ten millimeters in water. This is because the glass fibers do not have a fixed orientation within the plane of the separator. Therefore, J
: The shape and size of the holes formed are not constant, and the holes are oriented perpendicularly to the surface of both electrode plates rather than vertically, so oxygen gas easily moves from the positive electrode plate to the negative electrode plate. In addition, in conventional lead-acid battery mats in which two groups of long fibers intersect at an angle of about 60 degrees, long and narrow holes are formed that are oriented diagonally at an angle of about 30 degrees with respect to the upper and lower vertical lines, and the positive electrode plate is It is difficult for gas to move from the to the negative electrode plate, and furthermore, the gel electrolyte tends to move up and down, so stratification tends to occur, which is undesirable.

In the battery according to the present invention, electrolytic fl! Dilute sulfuric acid, which is No. 2, is weakly combined with silica particles to form a gel-like structure and is well retained in the pores of the separator.Therefore, it is necessary for the separator to have high liquid retention, as in the case of a lidena battery. No. A separator with high liquid retention properties has thin fibers and a dense structure, so the pores are small, and if the gel electrolyte is filled therein, the movement of oxygen gas will be inhibited, which is rather undesirable.

When comparing a positive electrode plate and a negative electrode plate, the power of holding the electrolyte, that is, the liquid retention capacity, is generally greater in the positive electrode plate.

This means that the surface area per gram of active material is approximately 5r on the positive electrode plate.
A. This is because the negative electrode plate has a larger value of approximately 0.511. In the battery of the present invention, the dilute sulfuric acid that is the electrolytic solution is weakly combined with the silica fine powder to form a gel-like structure, so the liquid retention capacity of the separator may be smaller than that of the negative electrode plate. A separator with a low liquid retention property has a large pore diameter and a loose structure, so even when filled with a gel electrolyte, there are voids and oxygen gas can move through the separator, which is preferable. Here, the level of liquid retention is determined by placing the electrode plate and separator in close contact with each other in a sealed container, injecting a small amount of dilute sulfuric acid into the container, and measuring the electrolyte held by the electrode plate and separator after purchasing. demand.

The level of liquid retention can be determined by the value obtained by dividing the amount of electrolyte retained by the electrode plate and lever by the volume of each hole.

Methods for gelling the electrolyte include adding and suspending silica particles with an average diameter of 20 mm or less in dilute sulfuric acid, and adding dilute sulfuric acid to colloidal silica, which is made by suspending silica particles in water. There is a method of stirring to form a sol. In the former case, silica particles often aggregate and are large;
When the electrolytic solution is injected into the cell, only the liquid component is impregnated into the electrode plate or separator, leaving silica particles on the top, which is undesirable. In the latter case, if a sol electrolyte is injected into the cell containing the electrode group, the fine silica particles will not be filtered by the separator, so the separator and part of the side of the electrode group will contain approximately the same concentration of silica. This is preferable. However, the pores of the active material are extremely small, and even in this case, only a small amount of silica particles can enter the active material. Therefore, in order to retain a gel of 3 to 7 weight percent silica in the pores of the separator, the amount of colloidal silica injected into the battery must be
It is preferable to use a mixed sol with sulfuric acid in which the amount of silica is 2 to 5 percent by weight.

In the present invention, it is important to have a gel electrolyte in a part of the side part of the electrode plate group and to have a void in the other part. Sealed batteries have a small amount of liquid, and when the sulfuric acid inside the electrode plate group is consumed during deep discharge and becomes neutral, lead is eluted and a short circuit occurs, and the positive electrode plate is insulated at the interface between the lattice and the active material. The problem is that layers form. At this time, sulfuric acid gradually diffuses from the gel electrolyte on the side of the electrode group, preventing the liquid inside the electrode group from becoming neutral, and preventing the formation of seams 03-1~ and an insulating layer. . Furthermore, when repeated deep discharges cause a stratification phenomenon in which the electrolyte at the bottom of the plate group becomes highly concentrated and the concentration at the top becomes low, the water vapor pressure axes from above and below occur in the voids on the sides of the plate group. Stratification can be eliminated by allowing the movement of water vapor, where water evaporates at the top and is absorbed at the bottom.

Effects of the Invention The present invention can improve the sealed reaction efficiency, discharge capacity, and deep discharge cycle life performance of a sealed lead-acid battery.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of a sealed lead-acid battery according to the present invention.

Claims (1)

[Claims] 1. An electrode plate group is constituted by a positive electrode plate, a negative electrode plate, and a separator consisting of a flexible flat porous plate mainly made of glass fiber with an average diameter of 5 to 25 microns, and the electrode plate group is It is stored in a battery case equipped with a valve in a strongly compressed state, and 3 to 30% of silica particles are applied to at least the holes of the separator and a part of the sides of the electrode plate group.
A sealed lead-acid battery using an oxygen cycle, in which a gel-like dilute sulfuric acid electrolyte having a concentration of 7% by weight is present, and a gap is provided in a part of the side of the electrode plate group. 2. The sealed lead-acid battery according to claim 1, wherein the fibers constituting the separator are in the form of a nonwoven fabric that does not have a fixed orientation in a plane. 3. Cathode active material in descending order of dilute sulfuric acid electrolyte retention capacity,
The sealed lead-acid battery according to claim 1, wherein the negative electrode active material and the separator are arranged in this order. 4. Gel-like dilute sulfuric acid electrolyte is a mixture of colloidal silica and dilute sulfuric acid, in which fine silica particles are suspended in water, and is injected into the battery containing the electrode plate group and gelled. A sealed lead-acid battery according to claim 1.