JPH04155759A - Manufacturing method for positive electrode plates for lead-acid batteries - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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 lead-acid battery, and more particularly to improving the aging conditions of a paste-type electrode plate after applying the paste.

Conventional technology Plate plates for lead-acid batteries generally have lead powder, water, and sulfuric acid as their main components, to which short fibers such as resin, fine carbon powder, organic additives, etc. are added as necessary, and they are made by kneading. Apply the obtained paste to a cast lattice body or a continuous expanded lattice body,
Paste-type electrode plates are often used, which are cut into the shape of the electrode plate as needed, aged and dried in a suspended state, and then made into an electrode plate.

In this aging and drying stage, the metal lead in the lattice and paste is oxidized and then dried to strengthen the bonds between the active material and the lattice and between the active materials and to generate tribasic lead sulfate. There is.

Conventionally, at this stage of ripening, the moisture content of the paste was reduced to 5 to 8.
% range for a long period of time. Therefore, if the electrode plates are aged in close contact with each other without heating, the electrode plates can be manufactured in a somewhat stable state. However, it has the drawback of requiring a long time for drying. Therefore, if you separate the electrode plates one by one and heat them in a suspended state to accelerate the reaction rate, the evaporation of water will also be faster, so the moisture content can be reduced to 5 to 8%.
In order to maintain this level, a method is used in which humidification is performed during the initial stage of ripening and drying, followed by drying.

Problems to be Solved by the Invention In the above-mentioned conventional configuration, there are large variations within a lot due to the spacing and location of the suspended electrode plates, the elapsed time after application, etc., and even between lots, the initial state of the paste, that is, the overall It is inevitable that fluctuations will occur depending on the temperature, moisture content, etc. Furthermore, since the ripening and drying speed varies depending on the thickness of the electrode plate, different patterns of ripening and drying were required for each set thickness.

Means for Solving the Problems In order to solve these problems, the method for manufacturing a positive electrode plate for a lead-acid battery of the present invention includes suspending the electrode plates in close contact with each other in the thickness direction of the electrode plates during the aging stage. Humidification is performed from the time when the surface temperature of the interpolated electrode plate () rises by 3° C. above the ambient temperature, and then it is dried.

Effect: With this configuration, the method for manufacturing a positive electrode plate for a lead-acid battery of the present invention is as follows:
By bringing the electrode plates into close contact with each other, it is possible to reduce fluctuations due to spacing and location in the suspended state, suppress excessive moisture evaporation due to heating, and eliminate the need to consider the effect of ridge plate thickness. . In addition, the best bonding strength between active materials and between active materials and lattice bodies can be achieved by humidifying when the surface temperature of the electrode plate rises by 3°C or more above the ambient temperature due to heat generated during oxidation of lead metal. It will be. This also makes it possible to shorten the ripening and drying time. Furthermore, heat generation during oxidation occurs when the reaction efficiency reaches 15 to 8% (15 to 8% moisture content is reached, so humidification from that point onwards means that the temperature, moisture content, and coating temperature at the previous stage of synthesis are the same). Do not take into account changes such as the passage of time since (
This means that you can maintain the best moisture content. This makes it possible to strongly stabilize the bonding strength between the active material and the lattice and between the active materials.

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

Oxidation degree 72? A mixture of 100 kg of lead oxide powder of
0. ,'l,i A paste made by adding 10C of distilled water is applied to the cast grid body and overlapped, and on both ends, a material that does not allow water vapor to pass through and has the same shape as the electrode plate is placed over the ends and the center. Do a pull-up without changing the condition of the parts. We put it in a drying oven with a preset temperature of 65℃, measured the temperature on the surface of the electrode plate in the center, and when the temperature reached 68℃, we started adding 90% humidity and kept it humidified for 8 hours. continue. Thereafter, humidification was stopped and the plate was dried at the same temperature for 8 hours, which was designated as electrode plate A. At this time, the electrode plate made under the same conditions as electrode plate A was suspended in the same way as electrode plate A until the surface temperature of electrode plate A reached 68°C, which took 1 hour for 6 coatings, and the temperature reached 65°C.
It was kept under 90% humidity for 9 hours, and then kept at 65℃ for 8 hours.
The plate that has been dried for a period of time is referred to as electrode plate B. Further, the electrode plate C was prepared under the same conditions as A until coating, suspended at appropriate intervals, and aged and dried in the same pattern as B. 1st
The figure shows the relationship between the rise in temperature of the electrode plate surface and the amount of falling off against the ambient temperature at the start of humidification.As is clear from Fig. 1, if humidification is started when the temperature rise is not sufficient,
The bond strength between active materials and between active materials and lattice bodies is weak (
Also, since the variation is large, it is necessary to start humidification when the temperature of the electrode plate surface rises by 3° C. or more above the ambient temperature.

The test conditions in FIG. 1 are the same as those in FIG. 4, which will be described later.

Figure 2 shows the change in moisture content in the active material during aging and drying of these three types of electrode plates, and Figure 3 shows the change in the amount of metallic lead in the active material.
As shown in the figure. As is clear from Figures 2 and 3, the electrode plate B
In Plate C, the amount of metallic lead decreases, that is, oxidation progresses, but the amount of moisture decreases slowly (and drying does not finish in the same amount of time. In Plate C, the amount of moisture decreases quickly, but the amount of metallic lead decreases slowly, i.e. Oxidation has not progressed.Furthermore, the variation in the final amount of metal lead in plates B and C is larger than that in plate A.In other words, lead acid is added to strengthen the bonds between the active materials and between the active materials and the lattice. It is thought that the oxidation of the compound powder was not uniform.Also, to confirm the strength of the bond, the drop strength was measured.Five electrode plates A, B, and C were randomly pulled out and placed on concrete from a height of 80 cm. It was determined by the amount of active material that fell off the top five times (Figure 4).As is clear from Figure 4, Plate B was not completely dried, so a very large amount of active material fell off. Plate C had a large variation in the amount of falling and falling off.In addition, in order to confirm the effect of the difference in bond strength on battery performance, 100 batteries each with a capacity of 2.0 Ah were made using Plate A and C. 40
The discharge capacity was measured after being left at ℃ for one month (Figure 5). Fifth
As shown in the figure, among the batteries made with the electrode plate C, there were three batteries with a discharge capacity of only 0.6 Ah to 1.2 Ah. Analysis of these three batteries revealed that the positive electrode potential suddenly became less base in all cases, and the electrode plate had a large amount of lead sulfate in a layer on the lattice surface and inside the active material, despite the charged state. It was generating. This phenomenon was not observed in the batteries made from plate A or plate C, which had a high capacity.

This is thought to be because dilute sulfuric acid, which is an electrolytic solution, concentrated and entered the parts where the bond between the active material and the lattice and between the active materials was originally weak, producing inactive lead sulfate.

Effects of the Invention As is clear from the description of the embodiments above, according to the method for producing a positive electrode plate for a lead-acid battery of the present invention, the electrode plates are suspended in close contact with each other in the thickness direction during the aging and drying stage. Humidification is performed from the time when the surface temperature of the electrode plate rises by 3°C or more above the ambient temperature, and then drying reduces the variation in the amount of water and the amount of metal lead in the active material in the aged state. It is possible to reduce variations in performance and further shorten aging and drying time.

[Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between the temperature rise on the surface of the electrode plate and the amount of falling off relative to the ambient temperature at the start of humidification in the manufacturing method of a positive electrode plate for a lead-acid battery according to an embodiment of the present invention, and FIG. A graph showing changes in the amount of water in the active material due to differences in aging and drying conditions between the manufacturing method of a positive electrode plate for a lead-acid battery according to an example and a comparative amount. Figure 4 is a graph showing the amount of active material falling off due to differences in aging and drying conditions. Figure 5 is a graph showing variations in discharge capacity after storage due to differences in aging and drying conditions. This is a graph showing. Name of agent: Patent attorney Haruaki Ogata and two others Figure 1: Ih3R &IEliM%,;MJ1; Missing R
Mouth 11d pseudo a+JJ￥ k4 ('c>Figure 2 G5 and light descendant BJ! ()l) Figure 4

Claims (1)

[Claims] In the maturing stage of positive electrode plates for lead-acid batteries, a paste made by kneading lead oxide powder containing metallic lead, water, and sulfuric acid as main ingredients is applied to a cast grid or continuous expanded grid, aged, and dried. A positive electrode plate for a lead-acid battery is made by suspending the electrode plates in close contact with each other in the thickness direction of the electrode plates, humidifying the electrode plates from the time when the surface temperature of the electrode plates in the middle of aging rises by 3°C or more above the ambient temperature, and then drying them. Manufacturing method.