JP2918204B2 - Sealed lead-acid battery - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement of a sealed lead-acid battery.

2. Description of the Related Art A closed lead storage battery of the negative electrode absorption type is a battery characterized in that dilute sulfuric acid in an electrolytic solution is substantially immobilized and oxygen gas generated from a positive electrode during charging is absorbed by a negative electrode active material.
In addition, the gas is hardly discharged to the outside of the battery, so that maintenance such as water refilling is not required, and it is maintenance-free. In addition to being position-free due to no liquid leakage, it is a more compact type. As a result, it has rapidly expanded as a backup power supply for OA equipment, and has greatly improved safety and reliability compared to conventional liquid lead-acid batteries.

The electrolyte holder and separator used in this sealed lead-acid battery ensure the conductivity between the positive electrode and the negative electrode, hold the sulfuric acid necessary for the battery capacity, and between the two electrodes during charging and discharging. It is necessary to have a characteristic of smoothly supplying and absorbing water. Furthermore, it is necessary that oxygen generated at the positive electrode during charging has a space capable of moving to the negative electrode, and that the absorption reaction on the negative electrode plate is sufficiently performed.

At present, in order to obtain a sealed lead-acid battery having these functions, the following electrolytic solution holding method is generally employed.

(1) A method in which glass fiber or the like is mixed to form a non-woven cloth, and an electrolyte is absorbed and retained in the non-woven cloth (hereinafter, referred to as a “retainer type”).

(2) A method in which the electrolyte is held by a gel made of an inorganic oxide such as silica (hereinafter, referred to as a gel type).

(3) A method in which an acid-resistant inorganic powder is contained in glass fibers or synthetic fibers (hereinafter referred to as "powder type"). A retainer-type electrolytic solution holder is a mixture of fine glass fibers, synthetic fibers, and binders. Nonwoven fabric.
The configuration of the electrolyte holder is, for example, an electrolyte of 70 to 80% by volume,
Consists of 5-10Vol% glass fiber and 15-20Vol% space. Therefore, the movement of the liquid is easy, the battery characteristics are good, and the oxygen gas is sufficiently absorbed by the negative electrode. Most of the present negative electrode absorption type lead-acid batteries are of the retainer type.

On the other hand, in the gel method, silica particles are mixed with dilute sulfuric acid to form a gel, which tends to hinder the movement of oxygen gas and gas absorption at the negative electrode. It tends to adversely affect battery characteristics such as separation. In addition, the manufacturing process becomes complicated, leading to an increase in cost.

By the way, in the sealed type lead-acid storage battery,
In particular, in the case of a large-capacity specification, the electrode plate becomes large, and a so-called stratification phenomenon occurs in which the concentration of the electrolyte at the top of the battery is low and the concentration of the electrolyte at the bottom is high due to charging and discharging. This is difficult to solve, and is a major cause of lowering battery performance and shortening the service life. For this reason, a gel-type large-capacity battery has been considered, but as described above, it has not been a high-performance battery due to characteristics and manufacturing problems.

On the other hand, it has been found that the powder-type electrolyte holder can suppress the stratification of the electrolyte, and is a battery showing sufficient characteristics as a sealed lead-acid battery. Research is progressing rapidly as a sealed lead-acid battery that is being developed, and it is being developed for commercialization.

Problems to be Solved by the Invention In the electrolyte holding body mainly composed of inorganic powder and various fibers,
In order to prevent stratification, the content of each type is examined, and specifications suitable for batteries are determined.

Conventionally, since a retainer-type electrolytic solution holder is expensive, it has been studied with a primary focus on cost reduction by including an inorganic powder. The aim was to reduce costs by making the glass fiber thicker.

However, as a problem in handling, cracking of the electrolytic solution holder and falling off of the powder have occurred, and as a countermeasure, the addition of fibril-like synthetic fibers and the increase of the synthetic fibers themselves have been performed. This has been manifested as an increase in cost and a decrease in battery performance due to an increase in materials having low renewability with sulfuric acid.

In addition, the cost is reduced by further increasing the amount of powder.However, the electrolyte holder itself becomes harder and the powder drops off, and the powder inside the holder exists as a large lump. As a result, problems such as a decrease in retention and supply of the electrolytic solution occurred.

As described above, attempts are being made to solve the various problems to make a cheap electrolyte solution holder, but the composition is complicated and the expected effect is unlikely to appear, and conversely, the cost is even increased due to complicated manufacturing specifications.

Means for Solving the Problems The present invention has been made in order to solve the above-mentioned problems, and an inorganic powder made of acid-resistant silicate powder and diatomaceous earth as raw materials for glass fibers having an average diameter of only less than 1.0 μm. Is used as an electrolyte holder.

Action The present invention has the above-mentioned features, simplifies the process by limiting the type of glass fiber to an average diameter of less than 1.0 μm, and uses a large amount of 40 to 70% by weight of silica powder and inorganic powder made from diatomaceous earth. An object of the present invention is to provide a sealed lead-acid battery provided with an electrolytic solution holding body that can reduce the cost of the material and the manufacturing cost and improve the problem of stratification of the electrolytic solution.

Example An example of the present invention will be described.

As shown in the composition of the electrolyte holder in Table 1, glass fibers have an average diameter of 0.7 μm, 4 μm, and 16 μm, and inorganic powders such as silicate powder and diatomaceous earth are mixed and stirred with pure water, and then dried after papermaking. Thus, an electrolyte holder made of a porous body having a thickness of 2.4 mm was prepared.

A 200 Ah sealed lead-acid battery was manufactured using these electrolyte holders and a 250 mm-high electrode plate. After injecting an electrolytic solution with a specific gravity of 1.300 and checking the battery capacity, "Discharge 40A (0.2C
A), 8 hours; charge test 60 A (0.3 CA), charge voltage 2.45 V / cell, 8 hours; temperature 20 ° C. " After 10 cycles, the battery was disassembled, the specific gravity of the upper and lower parts of the battery electrode plate was measured, and the specific gravity difference was measured.

According to the results shown in Table 1, in the case of glass fibers having an average diameter of less than 1.0 μm, stratification of the electrolytic solution is suppressed when the amount of the inorganic powder is 40 to 70% by weight. Generally, the problem of stratification is when the specific gravity difference is 0.05 or more,
Between 0.05 and 0.05 is considered a cautionary level.

About the thickness of the glass fiber, for example, average diameter 4.0μ
When m is mixed, the difference in specific gravity becomes large, and it becomes a level to be noted depending on the type of battery. When no glass fiber of less than 1.0 μm is contained, the difference in specific gravity is obviously large. As described above, it was found that when glass fibers having an average diameter of 1.0 μm or more were included, stratification was increased.

As described above, according to the present invention, the average diameter is 1.0 μm.
Because a porous body containing 40 to 70% by weight of acid-resistant silicate powder and diatomaceous earth-based inorganic powder in glass fiber of less than m is used as the electrolyte holder, the electrolyte is layered in a sealed lead-acid battery. And the cost can be reduced by using a large amount of inorganic powder.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-221954 (JP, A) JP-A-61-80750 (JP, A)

Claims (1)

(57) [Claims] 1. An acid-resistant silicic acid powder and an inorganic powder made from diatomaceous earth are mixed with glass fibers having an average diameter of less than 1.0 μm.
A sealed lead-acid battery using a porous body containing 40 to 70% by weight as an electrolyte holder.