JPS60148052A - Sealed lead storage battery - Google Patents

Abstract

PURPOSE:To prevent any lack of conductivity and any minute short circuits which might be caused by the use of a pulverized positive active material so as to increase the life of a sealed lead storage battery by using a separator having a double structure consisting of a positive-side layer with a given maximum hole diameter and a negative-side layer with a given maximum hole diameter. CONSTITUTION:A separator made of minute glass fiber has a double structure consisting of a positive-side layer and a negative-side layer. The maximum hole diameter of the positive-side layer is adjusted to 5-10mum and that of the negative-side layer is adjusted to 20-40mum. Therefore, even when a pulverized positive active material is used, the decrease in the conductivity of the positive active material can be suppressed by firmly holding it. Additionally, due to the small hole diameter of the separator, any permeation of minute particles of the active material into the separator is prevented. Accordingly it is possible to increase the life of a sealed lead storage battery by preventing any lack of conductivity and any minute short circuits.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to improvements in sealed lead-acid batteries, particularly large current discharge batteries for portable equipment.

Conventional configurations and their problems Sealed lead-acid batteries are used as power sources for many portable devices because of their high cost efficiency and ease of handling. Particularly recently, it has been used as a power source for large current discharge type portable devices such as electric tools of 60 to 2 oC.

When used in this type of application, there are the following problems. That is, when discharged with a large current, there is a significant difference in how the active material of the positive electrode is utilized in the reaction in the thickness direction of the electrode plate, and almost only the surface contributes to the reaction. For this reason, when charging and discharging are repeated, the active material on the surface of the positive electrode plate becomes finer, and as a result, the active materials lose their bonding strength with each other, resulting in a decrease in conductivity.The finer active material soaks into the inside of the separator. They have the disadvantage of causing short circuits with the negative electrode and premature deterioration of the battery.

Purpose of the Invention The purpose of the present invention is to eliminate the above-mentioned conventional drawbacks, prevent lack of conductivity and micro-short circuits due to fine particles of the positive electrode active material, and provide a long-life sealed lead-acid battery. .

Structure of the Invention The present invention uses a separator made of fine glass fibers in a double structure to separate the characteristics of the parts facing the positive and negative electrodes, so that the surface with smaller pores contacts the positive electrode and the surface with larger pores contacts the negative electrode. It is characterized by what it did.

With such a configuration, the lack of conductivity due to the fineness of the positive electrode active material can be suppressed by firmly holding it, and the penetration of the fine particle active material into the separator can be suppressed. However, since the pore size is small, it acts as a resistance to migration and can prevent this.

Description of examples The present invention will be explained in detail below.

(Example 1) ``As a positive electrode plate, a lattice made of Pb-C'a-8n alloy was filled with a paste made by kneading lead oxide, water, dilute sulfuric acid, etc. Size 46 tuna, height 5
5 Prepare mackerel. Pb-Ca-8n as negative electrode plate
Lead oxide and barium sulfate on an alloy lattice.

Filled with a paste made by kneading organic additives, water, dilute sulfuric acid, etc., and chemically formed to a thickness of 1.51111. Length 45cm, height b
ESMRA products were prepared, and three and four pieces were combined, respectively, and the electrode plate spacing was set to 1.5 Alff+. A separator made of fine glass fiber is inserted between the electrode plates. The average thickness of the glass fibers used in this separator is 0.7 μm, or the density at the time of paper making is changed.
There were five types: 5, 10, 20, 30, and 40 μm.

Note that the conventional example corresponds to 30 μm. The electrolyte has a specific gravity of 1.
30 dilute sulfuric acid was used. This battery has a voltage of 12 V', a 10 hour rate capacity of 3, and oAh when compared to the conventional example.

These batteries were tested for liquid retention capacity, initial duration at 50 m discharge, charge/discharge cycle life test (charging; 2/45V7
．． , l/constant voltage, maximum current is 2.4 μm, charging time is 3 hours, discharge: 0.8 volts 2f resistance, final voltage is 9. OV, ambient temperature change: 25℃, end of life when capacity reaches % of initial value) depth of penetration of positive electrode active material into separator and storage test during charge/discharge cycle (40℃ every 5o cycles,
When the sample was left for 3 days), the results were as shown in Figures 1 and 2.

Accordingly, when the maximum pore diameter is small, penetration of the positive electrode active material is suppressed, and a configuration with extremely excellent charge/discharge cycle life characteristics can be obtained. However, on the other hand, it was found that the discharge duration was short.

(Example 2) Same configuration as Example 1 with electrode plate spacing of 1.5 and 1.0°0.
．． 5111M, and had a double structure of separators with maximum pore diameters of 10 and 30 μm, arranged so that the 10 μm surface was in contact with the positive electrode side, so that the thickness ratio was 1:1. As a comparison, a battery was prepared using a separator having a single layer structure with a pore diameter of 3 μm, and the same measurements and tests as in Example 1 were performed on these. The results are shown in FIGS. 3 and 4.

According to these, by using a double-structured separator, the charge/discharge cycle life is 1.6 to 2.
This is a remarkable improvement of 2 times, and it is also clear that there is little capacity loss due to being left in the middle of a charge/discharge cycle, which is a necessary characteristic in practical use and is proof of a slight short circuit. By arranging a separator with a small maximum pore size on the surface of the positive electrode plate, it is possible to retain the active material and suppress the penetration of particulate active material into the separator.

Here, the effect is remarkable when the electrode plate spacing is 11r1jl or less, and since it is necessary to narrow the electrode plate spacing in order to make the battery compact, the configuration of the present invention is such that the electrode plate spacing is 11. This is particularly effective when Tfii or lower.

In addition, regarding the maximum pore diameter of the separator, the layer facing the positive electrode is
The thickness of the layer facing the negative electrode is preferably 20 to 40 μm, considering the liquid retention capacity and mass productivity of the separator, since strength decreases if the layer exceeds 40 μm.

Effects of the Invention As is clear from the above examples, the battery of the present invention has the following effects:
It has great industrial utility value, such as improved charge/discharge cycle life and less loss of capacity due to being left unused during a charge/discharge cycle, which is a practical characteristic.

[Brief explanation of drawings]

Figure 1 shows the charge/discharge cycle life, initial discharge duration, and liquid retention capacity for each maximum pore diameter of the separator, and Figure 2 similarly shows the penetration depth of the positive electrode active material and the capacity loss due to neglect during the charge/discharge cycle. Figure 3 is a diagram showing the charge/discharge cycle life, initial discharge duration, and liquid holding capacity for single and double separators according to the electrode plate spacing, and Figure 4 is a diagram showing the penetration depth of the positive electrode active material. FIG. 3 is a diagram showing the relationship between battery life and capacity reduction due to being left unused during a charge/discharge cycle. Name of agent: Patent attorney Toshio Nakao and one other name:
Figure No. 1 Shakukoshi Saichi (μ Town Figure 2 Figure 3 Figure Type Itabashi side No. 4rIJJ 1, 6) Yuzuki Hat City (・~'

Claims (1)

[Claims] A positive electrode made of lead dioxide as an active material, a negative electrode made of spongy lead as an active material, and a separator made of fine glass fiber is interposed between them, and the electrolyte is occluded in these, and the electrode plate spacing is set to 1. This is a sealed lead-acid battery with a double-layer structure in which the layer facing the positive electrode has a maximum pore diameter of 6 to 10 μm, and the layer facing the negative electrode has a maximum pore diameter of 20 to 40 μm. A sealed lead-acid battery characterized by: