JPH01102860A - Sealed lead-acid battery - Google Patents

Abstract

PURPOSE:To prolong the life with charging/discharging cycles by making a positive electrode plate in clad type construction, putting a porous substance consisting chiefly of glass fiber in close contact with the surface of a negative electrode plate, and giving the SiO2 concentration of electrolyte inside the pos. and neg. electrode plates a value lower than that of electrolyte existing between the pos. and neg. electrode plates. CONSTITUTION:The SiO2 concentration in pores of positive and negative electrode plate active substance, to facilitate dispersion and movement of sulphuric acid. The SiO2 forms a three-dimensional skeleton and becomes gel, so that a greater SiO2 content provides more sturdy gel and gives sulphuric ions difficulty to move. To dissolve this problem, a porous substance consisting chiefly of fine glass fiber is arranged in close contact with the surface of negative electrode plate, and the gel-formed electrolyte is hindered from intruding into pores in the neg. electrode active substance. Here the porous substance prevents the gel-formed electrolyte from directly contacting the neg. electrode plate and exerts a function that fine pores in the porous substance filtrate SiO2 particles. This allows the neg. electrode plate to make electric discharge in electrolyte which is free of SiO2 substantially to lead to enhancement of the discharging performance.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to improvements in sealed lead-acid batteries, particularly sealed lead-acid batteries with clad positive plates.

Conventional technology and its problems Sealed lead-acid batteries have conventionally been classified into two types: those using a paste-type horizontal plate as the positive electrode plate and those using a clad-type electrode plate.

The former is characterized by excellent discharge performance, and the latter is characterized by long life performance, but these characteristics are different from liquid type (open type).
This is a feature also seen in lead-acid batteries. In conventional sealed lead-acid batteries with clad positive electrode plates, a synthetic resin separator or perforated plate is placed between the positive and negative electrode plates, and an electrolyte made of dilute sulfuric acid gelled with colloidal silica (SiO2) is used. Injected. Clad type electrode plates have a lower utilization rate of active material than single-skin type electrode plates, and in addition, when the electrolyte becomes a gel, the sulfuric acid is wrapped in gel and is firmly fixed, making it difficult to diffuse. Discharge capacity decreases considerably. Furthermore, regarding the negative electrode plate, there was a drawback that the gel electrolyte entered the pores of the active material, and the S:02 of the electrolyte deteriorated the diffusion and movement of the electrolyte, resulting in a decrease in discharge performance. In this way, in a clad sealed lead-acid battery using a gel electrolyte, there is a decrease in discharge performance due to the clad plate structure and a decrease in discharge performance due to the gel electrolyte itself. It was inevitable that the discharge performance would be considerably inferior to that of open lead-acid batteries.

Means for Solving the Problems The present invention aims to improve the discharge performance of a clad-type sealed lead-acid battery using a gel electrolyte, by using a highly concentrated sulfuric acid electrolyte to cover the diffusion delay, and to improve the positive and A feature is that a porous body having a filtering effect of SiO2 is arranged on the surface of the electrode plate so that an electrolytic solution containing less 5IO2ffi exists in the active material 1 inside the negative electrode plate.

Example Conventionally, in lead-acid batteries, the electrolytic solution, dilute sulfuric acid itself, is the active material, so the higher its concentration, the more lLi! It is known that capacity increases. However, liquid type (17tt release type)
! In the case of a pond, if the specific gravity of the electrolyte is too high, l! A specific gravity exceeding about 1.30 (at 20° C.) is rarely put into practical use because it increases self-fi charge and promotes passivation of the negative electrode. In the closed type, the amount of electrolyte is limited, so it is possible to use a specific gravity electrolyte rather than in the liquid type.

In particular, 1illll is gelled by adding colloidal silica and water glass! In the I electrolyte, the sulfate ions held by the van der Waals force in the framework of the three-dimensional network structure of SiO2 are difficult to diffuse, so a sufficient capacity cannot be obtained with a specific gravity similar to that of conventional electrolytes. In the case of gel electrolyte, the sulfuric acid specific gravity is 1.30 (20°C) or more, 1.
Conventional liquid type batteries (specific gravity 1.
25 to 1.30).

Next, a means of improving the discharge performance of a gel-type sealed lead acid battery is to lower the SiO2'fA degree in the pores of the active material of the positive and negative electrode plates to facilitate the diffusion and movement of sulfuric acid as much as possible. As mentioned above, 5iOz forms a three-dimensional skeleton and gels, so the more S+02ffi there is, the stronger the gel becomes, that is, the harder it is for sulfate ions to move. In order to eliminate this drawback, the present invention disposes a porous material mainly composed of fine glass fibers closely on the surface of the negative electrode plate to prevent gel-like electrolyte from entering the pores of the negative electrode active material. It is structured.

In this case, the porous body prevents the gel electrolyte from coming into direct contact with the negative electrode plate, and the fine pores of the porous body serve to filter the SiO2 particles. As a result, the negative electrode plate is made of substantially Si.
It becomes possible to discharge in an electrolyte in which almost no O2 is present. In addition, since the clad type positive electrode plate originally has a structure in which the surface of the active material is surrounded by a tube made of glass fiber or synthetic resin fiber, the tube has the same effect as a porous body in contact with the negative electrode plate. Therefore, no special measures are required.

Effects of the Invention The sealed lead-acid battery according to the present invention improves the poor discharge performance, which is a drawback of clad lead-acid batteries with gel electrolyte, and achieves a performance level equivalent to that of a clad type (open type) type. I was able to reach it. As a result, we were able to develop a high-performance sealed lead-acid battery with excellent charge-discharge cycle life performance, which is a characteristic of clad plates, which was not possible with conventional sealed lead-acid batteries.
It can also be used in fields such as forklifts and power storage.

Claims (1)

[Claims] 1. An electrode plate group consisting of a positive electrode plate, a negative electrode plate, and a porous body mainly composed of glass fibers interposed between these electrode plates.
It is a sealed lead-acid battery based on the oxygen recombination method, which is gelled by O_2 and does not have an electrolyte that flows substantially, and the positive electrode plate has a clad structure and the negative electrode plate has porous holes mainly made of the glass fibers on the surface of the negative electrode plate. A sealed lead-acid battery in which the electrolyte inside the positive and negative plates has a lower SiO_2 concentration than the electrolyte between the positive and negative plates.