JP2559610B2 - Method for manufacturing sealed lead acid battery - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a retainer-type sealed lead acid battery in which a dilute sulfuric acid electrolyte is absorbed and held in an electrode plate group.

Conventional technology and its problems A so-called retainer system characterized by arranging a liquid-retaining separator between the positive electrode plate and the negative electrode plate, and impregnating the separator with dilute sulfuric acid electrolyte to the extent that it cannot be freely released. Due to the demand for maintenance-free batteries, sealed batteries are used in various applications including portable devices,
Recently, expectations for large-sized sealed lead-acid batteries for stationary, automobiles, electric vehicles, etc. have increased. However, when the electrode group is composed of large-sized electrode plates, the concentration distribution of dilute sulfuric acid electrolyte becomes nonuniform when charging and discharging are repeated, so-called electrolyte layering phenomenon becomes remarkable, and life performance deteriorates. Tend. In order to prevent this stratification phenomenon,
A method of adding about 4% by weight of silicon dioxide or sodium silicate to gelate the electrolytic solution has been proposed, but the electrolytic solution loses fluidity in a short time, so that it is necessary to prepare the electrolytic solution frequently. However, there is a problem that the liquid injection process becomes complicated.

Means for Solving the Problems The present invention has been made in view of the above problems, and an object of the present invention is to provide a retainer type sealed battery having a long life in which stratification of an electrolytic solution does not occur easily and inexpensively. That is, in the sealed lead-acid battery, the dilute sulfuric acid electrolyte mixed with 0.1 to 0.8 wt% of sodium silicate is absorbed and held in the electrode plate group including the positive electrode plate, the negative electrode plate and the liquid absorbing separator. It is a thing.

Examples Examples according to the present invention will be described below.

Using a separator mainly composed of glass fibers with an average diameter of 5 microns or less and a large flat positive and negative electrode plate, the total height of the battery is about
A 700 mm unfilled battery was assembled. In this unfilled battery,
Dilute sulfuric acid electrolyte with a specific gravity of 1.26 (20 ℃) and silicon dioxide 3
Dilute sulfuric acid electrolyte with a specific gravity of 1.26 (20 ° C) added with weight percent, sodium silicate (a) 0.05, (b) 0.1,
(C) 0.2, (d) 0.4, (e) 0.6, (f) 0.8, (g)
Dilute sulfuric acid electrolytic solution with a specific gravity of 1.26 (20 ° C.) added with 1.0 weight percent was injected into each to obtain a 2V-500Ah retainer type sealed battery. With these batteries, the discharge depth is 75%,
The charge amount was 120% of the discharge amount and the charge and discharge were repeated at a temperature of 30 ° C. In addition, during this cycle test, a capacity test was appropriately performed to measure the capacity of the battery. In addition, specific gravity sensors were attached to the upper and lower parts of the electrode plate group, and the specific gravity of the electrolyte solution after charging was also measured.

Table 1 shows the relationship between the amount of silicon dioxide and sodium silicate added and the gelling time, Fig. 1 shows the relationship between the number of charge / discharge cycles and discharge capacity, and Fig. 2 shows the relationship between the number of charge / discharge cycles and the upper part of the electrode plate group. And the relationship with the electrolytic solution specific gravity in the lower part. Here, the gelation time means the time until the electrolytic solution gels and solidifies, or the time until the viscosity of the electrolytic solution becomes high to some extent.

As shown in Table 1, when sodium silicate was added in an amount of 1.0% by weight or more, the electrolytic solution was gelated in several hours as in the case of adding 3% by weight of silicon dioxide, and the workability was poor.

On the other hand, when the amount of sodium silicate added was 0.8% by weight or less, the viscosity of the electrolytic solution increased only after a few days, the gelation did not occur, and the workability was good.

In addition, from FIGS. 1 and 2, sodium silicate was
It can be seen that the addition of 1% by weight or more can prevent the stratification of the electrolytic solution and does not reduce the discharge capacity. In other words, it can be seen that if the viscosity of the electrolytic solution is above a certain level, stratification can be prevented even if it is not necessarily gelled. Therefore, the addition amount of sodium silicate is suitably 0.1 to 0.8 weight percent.

In addition, sodium silicate is cheaper than silicon dioxide, and is effective even when added in a small amount, which is advantageous in terms of cost.

Effects of the Invention As described above, the sodium silicate content of 0.1 to
By adding 0.8 weight percent, a sealed lead-acid battery with excellent life performance without stratification of the electrolytic solution is obtained,
Further, it is excellent in workability and cost, and its industrial value is extremely large.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the charge / discharge cycle number and the discharge capacity of the sealed lead-acid battery of the present invention in comparison with the conventional example, and FIG. 2 is the charge / discharge cycle number and the electrolyte solution above and below the electrode plate group. It is a figure which shows the relationship with specific gravity.

Claims (1)

(57) [Claims] 1. A hermetically sealed type characterized by absorbing and holding a dilute sulfuric acid electrolytic solution containing 0.1 to 0.8% by weight of sodium silicate mixed in an electrode plate group consisting of a positive electrode plate, a negative electrode plate and a liquid absorbing separator. Lead acid battery manufacturing method.