JPH0443563A - Manufacturing method of positive electrode plate for sealed lead-acid battery - Google Patents

Abstract

PURPOSE:To manufacture a positive plate of high reliability for a sealed lead-acid battery by taking out the plate after partial discharge in a jar under formation after plate formation, preliminarily drying the plate until the water content of the plate reaches the predetermined concentration for active material at the predetermined temperature, and further drying the plate at the predetermined temperature. CONSTITUTION:After plate formation, partial discharge is performed in a jar under formation. Then, the plate is taken out from the jar, and subjected to a preliminary drying process at temperature in the range of 30 deg.C to 40 deg.C, until a water content in the plate becomes 0.03 to 0.05 g per gram of active material. Thereafter, the plate is dried at temperature in the range of 150 deg.C to 200 deg.C. As a result, both residual and recovery capacity becomes high, and capacity dispersion becomes approximately con stant, irrespective of a shelving period. According to the aforesaid construction, the dispersion of battery performance can be reduced, and the stability of active material at an interface with a grid can be improved. In addition, an excessive capacity drop after shelving can be prevented, and the sealed lead-acid battery of high reliability can be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing a positive electrode plate for a sealed lead-acid battery, and in particular to an improvement in a drying method after completion of chemical formation.

BACKGROUND OF THE INVENTION Lead-acid batteries are used in various fields because they have a relatively high energy density and are economical compared to other batteries.

However, some problems remain regarding capacity recovery after being left unused. Conventionally, a positive electrode plate for a sealed lead-acid battery was taken out of the chemical conversion tank after completion of chemical formation, washed with water to remove sulfuric acid from the surface of the electrode plate, and then immediately dried in a drying oven at 105°C.

Problems to be Solved by the Invention However, in the conventional method of drying a positive electrode plate for a sealed lead-acid battery, the electrode plate is dried in a state in which a large amount of moisture is contained in the electrode plate. As a result, unstable lead oxide is likely to be generated in the positive electrode active material and the lattice interface with the positive electrode active material, resulting in the following drawbacks.

(1) Unstable lead oxides (e.g. t-Pb).

Pbox, etc.) generates PbSO4 with sulfuric acid during injection, but especially lead sulfate formed at the interface between the lattice and the active material.
If left for a long period of time, an insulating film layer is formed that does not recover even when charged, resulting in a decrease in capacity and large variations in capacity.

(2) The stability of the positive electrode active material itself decreases, resulting in increased self-discharge during storage and poor capacity recovery even after charging.

The present invention solves these problems and aims to provide a method for manufacturing a positive electrode plate for a sealed lead-acid battery with high reliability.

Means for Solving the Problems In order to solve the above-mentioned problems, the method for producing a positive electrode plate for a sealed lead-acid battery of the present invention is to provide a method for producing a positive electrode plate for a sealed lead acid battery of the present invention. Take it out from 30-40℃
The water content in the electrode plate is 0.03 to 1 g of active material at a temperature of
After pre-drying the electrode plate until it weighs 0.05g, 150 ~
It is dried at a temperature of 200°C.

Effect: With this configuration, lead sulfate is formed and stabilized at the interface between the grid of the electrode plate and the active material by partial discharge in the chemical formation tank, and the capacity is restored by charging after battery formation, and the
By pre-drying the electrode plate at 0℃ and then drying the electrode plate at 150-200℃ for a short time, unstable lead oxide is generated in the positive electrode active material and the lattice interface between the positive electrode active material and the positive electrode active material in high temperature and high humidity. This will prevent them from doing so.

EXAMPLE Hereinafter, a method for manufacturing a positive electrode plate for a sealed lead-acid battery according to an example of the present invention will be described with reference to the drawings.

After chemically forming the positive electrode plate for a sealed lead-acid battery in sulfuric acid with a specific gravity of 1.10 for 20 hours with an amount of electricity of 0.50 Ah per 1 g of active material, ■ After completing the chemical formation as a conventional method,
After washing the electrode plate with water, it is dried at 105° C. for 1.5 hours.

(2) As per this example, after completion of chemical formation, after discharging at a current of 0.02 A per 1 g of active material for 0.5 h, the electrode plate was washed with water, pre-dried at 40°C for 1 h, and then dried at 150°C for 0.25 h.
Perform drying. These two types of positive electrode plates were created and their battery performance was compared. The capacity of the battery is 10 hour rate capacity 0.2Ah,
The capacity test was conducted with a configuration determined by the capacity of the positive electrode plate.

Discharging is constant current equivalent to 0.8 CA, charging is 2.45 V/
Cell constant voltage charging was performed. In the battery configured according to the present embodiment (2), the amount of sulfuric acid is corrected and injected according to the amount of discharge,
The absolute amount of sulfuric acid was made to be the same amount as in the conventional method (■). The specific gravity of the injection type electrolysis was increased from the usual 1.34 to 1.40 for the purpose of accelerating capacity deterioration during storage. After creating the battery, it was charged and discharged, the initial capacity was measured, and then left at 40°C.

Fig. 1 shows a comparison of the remaining capacity ratio after being left at 40°C, and Fig. 2 shows a comparison of the recovered capacity ratio when performing voltage charging after measuring the remaining capacity.

The method according to this embodiment has a recovery capacity of 1 remaining capacity and is superior to the conventional method. In particular, with respect to the variation in capacity, in the conventional method, there is a tendency for the variation to increase as the standing period becomes longer, but in the case of the present embodiment, the value remains almost the same regardless of the standing period. This is considered to be due to the improved stability of the active material itself.

Quantitative analysis of the amount of PbO, the amount of Pb5n, and other residual PbO in the positive electrode active material before standing at 40° C. was performed and compared with the conventional method. Although there was no difference in the amount of PbSO4 between the present example and the conventional method, the pbo amount was reduced to 273 in the present example compared to the conventional method. This confirms that the stability of the active material in this example is improved. In the test results of residual capacity 9 recovery capacity after being left at 40° C. for 4M, a significant decrease in capacity occurred among those using the conventional method. It was found that this was caused by the formation of a lead sulfate barrier layer at the interface between the lattice and the active material during standing, and the discharge reaction being blocked by this barrier layer. This barrier layer did not recover even after charging, so its recovery capacity remained low.

On the other hand, in this example, the stability of the active material at the interface between the lattice and the active material was improved due to the partial discharge after chemical formation, so there was no decrease in capacity as seen in the conventional method.

Effects of the Invention As is clear from the description of the embodiments above, the method for manufacturing a positive electrode plate for a sealed lead-acid battery of the present invention reduces the amount of self-discharge during storage and reduces variation due to improved stability of the positive electrode active material. In addition, it is possible to prevent a sudden decrease in capacity after storage by improving the stability of the active material at the interface between the lattice and the active material, thereby providing a manufacturing method that can manufacture a highly reliable sealed lead-acid battery.

[Brief explanation of the drawing]

Figure 1 is a diagram showing a comparison of the remaining capacity ratio after being left at 40°C between the manufacturing method of a positive electrode plate for a sealed lead-acid battery according to an embodiment of the present invention and the conventional method, and Figure 2 is a comparison of the recovered capacity ratio. FIG. Name of agent: Patent attorney Shigetaka Awano and one other person* l'
M 7'ii'l (Town trip 1 bottle r% I'l (M)

Claims (1)

[Claims] After completing the electrode plate formation, after partially discharging in the formation tank, the electrode plate is taken out from the formation tank, and at a temperature of 30°C to 40°C, the water content in the electrode plate becomes 0.03 to 0.05g per 1g of active material. A method for producing a positive electrode plate for a sealed lead-acid battery, which comprises pre-drying the electrode plate to a temperature of 150°C to 200°C.