JPH0451471A - Sealed type lead acid battery - Google Patents

Abstract

PURPOSE:To enhance the discharge performance of a sealed type lead acid battery greatly by putting fully specific silica powder between electrode plates and around the electrode plate bunch, and impregnating granulated powder and separator with a sulphuric acid electrolyte in a proper amount for discharging. CONSTITUTION:Silica powder granulated to pore diameters of 10-500mum, wherein the capacity of pores of 1-50mum in dia. shares 45% of the total pore capacity, is put fully between electrode plates and around the bunch of electrode plates, and the granulated powder and separator are impregnated with sulfuric acid electrolyte in a proper amount for discharging.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a sealed lead-acid battery, and in particular to improvements in its electrolyte holder.

BACKGROUND OF THE INVENTION In recent years, sealed lead-acid batteries have become widely used as backup power sources for portable devices and computers. This type of sealed lead-acid battery is classified into a retainer type and a gel type depending on the electrolyte retention method. The retainer type is a method in which the sulfuric acid electrolyte is held in a porous separator made of paper mainly made of fine glass fibers, and the gel type is a method in which the dilute sulfuric acid electrolyte is turned into a gel using silicic acid and filled into the battery. be.

Problems to be Solved by the Invention In the case of a retainer type separator, the fine glass fibers that make up the main body of the separator are expensive, so the separator itself is also very expensive. For this purpose, separators replaced with synthetic resin fibers have been developed, but they do not have sufficient liquid retention properties.

On the other hand, in the case of a gel type, the preparation and filling of the gel is complicated, and the diffusion of sulfate ions within the gel is slow, so the performance is lower than that of conventional open type liquid lead acid batteries as well as cage type sealed lead acid batteries. was inferior.

In order to solve these problems, we investigated silica granulated powder as an electrolyte retaining material for sealed lead-acid batteries, and found that silica granulated powder can be used as an electrolyte retaining material. However, as the experiments progressed, several shortcomings became apparent. One of these is that in order to fill the silica granulated powder in the battery case up to the height of the electrode plate group, more electrolyte must be injected than in the case of a retainer type, but despite this, the amount of electrolyte It may not be possible to obtain an increase in capacity equivalent to the increase in capacity.

Means for Solving the Problems The present invention solves the above-mentioned problems, and provides a sealed lead-acid battery having an electrolyte holder that is inexpensive, has excellent liquid retention properties, and has excellent sulfuric acid diffusivity. be. The gist of this is that between the electrode plates and around the electrode plate group, holes with a diameter of 10 to 50
Fill and arrange silica powder that is granulated to 0 microns and have a pore volume of 1 to 50 microns that accounts for 45% or more of the total pore volume, and add 2 parts of sulfuric acid electrolyte in an amount necessary and sufficient for discharge. The purpose is to impregnate and hold the fine grain powder and separator. The present invention will be explained below based on examples.

Example Pb - Ca - Sn alloy plates and negative electrode grids were filled with ordinary positive and negative electrode pastes 1 to 1 and aged. After that, an electrode plate group was prepared with three positive electrode plates and four negative electrode plates, and the electrode inserted into the tank. Here, the distance between the two electrode plates is approximately 1.5th+
A synthetic resin plate was used to hold the battery, but any material that is harmless to the battery and that maintains the distance between the two electrode plates will suffice. It is preferable to use a material that occupies a small volume between the two electrode plates.

Then, using fine silica powder and ice crow as a binder,
B with the amount of hydraulic lath changed to 2%, 5%, 10%, and 20%
Four types of silica granulated powders, C, D, and E, were prepared. In other words, add hydrolase, which has been thoroughly dissolved in water at the above ratio, to fine silica powder, make a paste, and dry at about 200°C! After L7, crush it and classify it with a shaker to get a diameter of 10-5.
A granulated silica powder having a diameter of 0.00 μm was obtained. The pore size distribution of these silica granules was measured using a mercury intrusion porosimeter. The results are not shown in Table 1. The measurement results of fine silica powder A before granulation are also shown.

Table 1 The particle size of the fine silica powder used in this example is 10 to 40.
Because the diameter of the pores is millimicrons, the volume of pores with a diameter of 0.1 micron or less accounts for more than 50% of the total pore volume.
Granules made using hydraulic lath as a binder have a diameter of 0.1 micron or more.1 The volume of these pores is 35% of the total pore volume.
%, and the percentage decreased as the amount of hydraulic lath increased. On the other hand, the volume of pores with a diameter of 1 to 50 microns was only 13% of the total pore volume in fine silica powder, or the volume of pores with a diameter of 1 to 50 microns was granulated using hydraulic lath as a binder. The volume is the total pore volume of 45
% or more, and as the amount of hydraulic lath increases,
The proportion has increased. This is because the binder enters the voids between fine silica powder and fixes the particles, fills the voids and reduces the volume of pores with a diameter of 0.1 microns or less, and granulated particles with a diameter of 10 to 500 microns. The pores with a diameter of 1 micron or more formed between the particles were newly formed, and the volume of the pores relative to the unit weight and unit volume of the silica did not decrease by granulation.

The silica granulated powder produced in this way was densely packed between the two electrode plates and around the electrode group while applying vibration. After the lid was glued, an exhaust valve was attached and the nominal volume was set to i, 1.5Ah. A sealed lead-acid battery was assembled. After injecting a sulfuric acid electrolyte into the thus assembled battery and performing chemical conversion, an initial capacity test was conducted. For comparison, retainer type and gel type batteries were also fabricated using the same positive and negative electrode plates, and capacity tests were conducted at the same time. The results are shown in Table 2.

Batteries B~, 1 according to the present invention? , had better 5-hour rate and efficient discharge performance than Battery A using non-granulated silica fine powder. It also showed superior performance compared to conventional retainer-type batteries D and Kel-type batteries G that use conventional glass separators. This is considered to be because the diffusion distance of the electrolytic solution held in the powder became shorter due to the reduction of small pores of 0.1 micron or less, making it easier to contribute to the discharge reaction.

Table 2 means that the surface area decreased (1), and the time required for injecting the electrolyte was also significantly shortened.

Effects of the Invention As mentioned above, between the electrode plates and around the electrode plate group, 10 to 5
Fill and arrange silica powder with a pore diameter of 1 to 50 microns or more than 45% of the total pore volume, and add a sufficient amount of sulfuric acid electrolyte for discharge = L
By impregnating and retaining the granulated powder and separator, the discharge performance of sealed lead-acid batteries can be greatly improved, and its industrial value is extremely large.

Claims (1)

[Claims] 1. A sealed lead-acid battery in which oxygen gas generated during battery charging is absorbed by the negative electrode, with granules of 10 to 500 microns between the electrode plates and around the electrode plate group, with pores of 1 to 50 microns in diameter. A silica powder having a volume of 45% or more of the total pore volume is filled and arranged, and the granulated powder and separator are impregnated and retained with a sufficient amount of sulfuric acid electrolyte necessary for discharge. A sealed lead-acid battery.