JPS6322015B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a paste-type electrode for lead-acid batteries.

Currently, the most popular type of secondary battery is a lead-acid battery, and among these lead-acid batteries, so-called paste-type lead-acid batteries, in which the electrode plates are obtained by applying paste to a grid, are the mainstream. The first reason for this is that the manufacturing method is simple and the electrode structure is simple, so the price is low. The second reason is that it has excellent performance.

The present invention provides such a paste type lead acid battery,
This provides an effective manufacturing method that allows the performance to be significantly improved compared to conventional methods.

Conventionally, this paste-type electrode plate is made by filling a support such as a lead or lead alloy grid, punched metal, or expanded metal with lead paste containing lead powder, water, and dilute sulfuric acid as its main components, and then drying it. It can be manufactured through relatively simple processes such as aging, and the discharge characteristics of the obtained electrode plate are quite good. However, it is desired to further improve the characteristics, for example, in terms of high rate discharge characteristics and discharge utilization rate of the active material.

From this point of view, various improvements have been considered, but the paste conditions of the electrode plate are the biggest factor that influences the electrode characteristics. Therefore, over a long history, a wide range of compositions have been studied, centering on the main components of lead powder, water mixed with it, and sulfuric acid.In recent years, in particular, mechanical paste filling has been involved, and paste filling has become more popular. A desirable composition that can be efficiently carried out and at the same time applicable to various battery specifications has been sought and reached at present.

However, as mentioned above, the desire from battery users to develop batteries with higher capacity, higher output, and higher reliability has led to the need to develop batteries that have higher capacity, higher output, and higher reliability. Improvements within the paste conditions, mainly based on the application conditions and composition, have reached their limits and have forced us to deviate from common sense. Therefore, in order to develop batteries with higher output, higher capacity, and higher reliability, it is necessary to
Improvements in aspects other than paste conditions have become necessary.

Therefore, the present invention provides a battery with extremely high performance and high reliability by improving the drying conditions. That is, the present invention allows the paste to be applied and filled onto a support and then dried in an atmosphere containing carbon dioxide gas in a larger amount than in the natural atmosphere, whereas conventional methods require drying in the natural atmosphere. It is a feature.

According to this manufacturing method, a porous plate with a shape that promotes the discharge reaction during high rate discharge is generated on the surface of the paste (active material) in the electrode plate after coating and filling, thereby increasing the capacity. It is measured. The porous material formed on the surface of the electrode plate can be presumed to be basic lead carbonate, but in order to bring it into the optimal state for the discharge reaction, the carbon dioxide gas in the atmosphere, temperature, exposure time, etc. must be adjusted during the drying process. It is necessary to keep it. Based on experimental facts as shown in Examples below, the present inventors have determined that during the drying process, the atmospheric carbon dioxide concentration is 10% or more and less than 80%, the atmospheric temperature is +5°C or more and less than 40°C, and the exposure time is preferably 1.
It has been found that conditions in which the relative humidity of the atmosphere is 40% or more and less than 80% for a period of time or more are suitable. The present invention will be explained below with reference to Examples.

Example 1 A positive electrode plate was manufactured by filling an expanded metal grid with a width of 135 mm, a height of 110 mm, and a grid thickness of 1.4 mm with a paste. For drying after rejuvenating the paste on the grid, the carbon dioxide concentration in the atmosphere should be adjusted to 1%, 5%.
%, 8%, 10%, 15%, 20%, 30%, 40%, 50
Electrodes were manufactured and batteries were assembled under 15 different drying conditions: %, 60%, 70%, 80%, 85%, 90%, and 95%. The other conditions of the atmosphere at this time were: temperature was 20℃, exposure time was 15 hours, and relative humidity was
It was 60%. Thereafter, it was aged in a conventional manner. The electrode plate group configuration of the battery is the above-mentioned four positive electrode plates and five negative electrode plates of the conventional configuration. The electrolyte has a specific gravity of 1.280
dilute sulfuric acid was used, and the liquid volume was 500 c.c. The test conditions were to discharge at a constant current of 300A to a terminal voltage of 1.0V/cell at a temperature of -15°C, and the discharge time at that time was measured.

FIG. 1 shows the relationship between atmospheric carbon dioxide concentration and battery discharge duration. As is clear from the figure,
It can be seen that the discharge duration is extremely short when the carbon dioxide concentration is less than 10%, and also becomes shorter when the carbon dioxide concentration is 80% or more. This shows that the effect is far different from, for example, the effect of carbon dioxide gas naturally present in the air. Even in X-ray diffraction analysis, it is not possible to detect a peak that seems to be caused by basic lead carbonate in an unformed plate that has been air-dried in air. The extent to which surface whitening occurs is also clearly visible. Although similar effects can be obtained in an atmosphere of carbon dioxide gas and air, it can be inferred that the presence of some oxygen has a favorable influence on the characteristics.

Example 2 Using the same grid as in Example 1, drying after filling the grid with the paste was performed by changing the ambient temperature to -5°C and 0.
℃, 3℃, 5℃, 8℃, 10℃, 20℃, 30℃, 40
Electrodes were manufactured under 13 different conditions (℃, 50℃, 60℃, 70℃, and 80℃) and batteries were assembled. In this case as well, this step of ripening was carried out in a conventional manner. Other atmospheric conditions at this time are carbon dioxide concentration of 30
%, exposure time 15 hours, and relative humidity 60%. The electrode plate group configuration, electrolyte solution, and test conditions are as in Example 1.
is the same as

FIG. 2 shows the relationship between drying ambient temperature and battery discharge duration. As is clear from the figure, when the ambient temperature is less than 5℃, the discharge time becomes shorter;
It can be seen that it becomes shorter even at temperatures above 40°C.

Example 3 Using the same grid as in Example 1, the drying atmosphere exposure time after filling the grid with paste was varied from 2 to 5.
8, 10, 12, 15, 18, 20, 25, 30, 35, 40, 45,
Instead of 50 hours, they produced electrode plates and assembled batteries under 14 different conditions. Other atmospheric conditions at this time were a carbon dioxide concentration of 30%, an ambient temperature of 20° C., and a relative humidity of 60%. The electrode plate group configuration, electrolyte solution, and test conditions are the same as in Example 1.

FIG. 3 shows the relationship between dry atmosphere exposure time and battery discharge duration. As is clear from the figure,
It can be seen that the discharge duration becomes short when the atmosphere exposure time is less than 10 hours, and also becomes shorter when the atmosphere exposure time is 40 hours or more. Separately, when the carbon dioxide concentration is increased to 80%, the effect can be seen even within 1 hour, as shown in Figure 3B.
Preferably, the time is 1 hour or more, and the result is that there is no significant difference between the time and the time. Conversely, when lowered to 10%, C shows that it does not decrease even with long-term exposure. In this way, depending on the carbon dioxide atmosphere, extremely short processing times are possible.

Example 4 Using the same grid as in Example 1, the relative humidity of the atmosphere during the drying process after filling the grid with paste was 10
%, 20%, 30%, 40%, 50%, 60%, 70%, 80
%, 85%, 90%, and 95%, and produced electrode plates and assembled batteries under 11 different conditions. Other atmospheric conditions at this time were a carbon dioxide concentration of 30%, an ambient temperature of 20° C., and an atmosphere exposure time of 15 hours. The electrode plate group configuration, electrolyte solution, and test conditions are the same as in Example 1.

FIG. 4 shows the relationship between the relative humidity of the atmosphere and the discharge time during the drying process. As is clear from the figure, the discharge duration becomes short when the relative humidity of the atmosphere is less than 40%, and even when it becomes 80% or more.

Example 5 First, a lead-calcium-tin alloy lattice was used in a conventional manner. Lead powder and water were mixed, and sulfuric acid was added dropwise to mix them into a paste. This paste was applied to the grid and then filled. Add this to 30 carbon dioxide gas
% in a chamber filled with air at 20° C. for 15 hours to dry, and then matured for 15 hours in a conventional manner to produce a positive electrode plate. The amount of kneading was made to be approximately equal to the value after ripening. A comparative test was conducted using the electrode plate dried in the carbon dioxide-containing atmosphere as D and the conventional electrode plate dried in the natural atmosphere as E.

These four positive electrode plates and five known paste-type negative electrode plates whose discharge capacity per plate is equal to that of the positive electrode are stacked alternately with polyethylene bag-shaped separators interposed to form a single cell, The specific gravity of the sulfuric acid electrolyte was adjusted to 1.27 upon completion of charging. These batteries at a temperature of -15℃,
A rapid discharge test was conducted with a current of 300A until the terminal voltage reached 1.0V. The test results are shown in FIG. As is clear from the figure, the discharge duration in the rapid discharge test was approximately 1.4 times longer for D than for E, and the discharge voltage (5th second voltage) was approximately 50 mV higher, indicating that It can be seen that drying has a great effect on improving performance.

As shown in some examples of the present invention, such an effect is caused by a chemical reaction that occurs through a step of contacting carbon dioxide gas after application of the paste, resulting in good properties. . In the examples, an example was shown in which the contact with carbon dioxide gas was carried out at the beginning of drying the paste, but it can be applied at any stage of the conventional ripening process. However, since the reaction is preferably carried out under moist conditions, in the case of a completely dry unformed plate, it is more effective to apply the present invention by moistening the plate by immersing it in water or by spraying it with water. As for the steps, as in the above example, the step of drying the paste can be used as is, so the number of steps is not increased and it is efficient. At the same time, since the treatment is carried out after the initial drying and before the composition of the porous body is determined, there is less risk of destroying the connections between the active materials, and the state of the product is slightly changed to a completely dried unformed board. Different cases apply. Therefore, it would be advantageous in controlling reliability. In the embodiment, a paste-type electrode plate using an expanded metal lattice was described, but the effects of the present invention are not limited to this embodiment, and the same effect can be obtained even if the lattice is made of cast metal or punched metal. The effect of this can be obtained.

As described above, according to the present invention, a porous body estimated to be made of basic lead carbonate that promotes the discharge reaction is formed on the surface of the active material, and the utilization rate of the active material in high rate discharge is increased. Therefore, high output and high capacity of the battery can be achieved, and the battery performance can be significantly improved.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between the carbon dioxide concentration in the drying process atmosphere and the rapid discharge duration of a lead battery, and Figure 2 is a diagram showing the relationship between the temperature of the drying process atmosphere and the rapid discharge duration of a lead battery. , Figure 3 is a diagram showing the relationship between the drying process atmosphere exposure time and the rapid discharge duration of the lead battery, and Figure 4 is a diagram showing the relationship between the relative humidity in the drying process atmosphere and the rapid discharge duration of the lead battery. , FIG. 5 shows a comparison of voltage changes during rapid discharge of lead batteries.

Claims (1)

[Claims] 1. After applying the paste to the support, in the dry aging process up to chemical charging, the carbon dioxide concentration is 10%.
80% or more, temperature 5℃ or more and less than 50℃, relative humidity
A method for producing a paste-type electrode for a lead-acid battery, comprising a step of exposing to an atmosphere of 40 to 80%. 2. The method for producing a paste-type electrode for a lead-acid battery according to claim 1, wherein the step of exposing to an atmosphere containing carbon dioxide gas is performed in an initial drying step after applying the paste. 3. The method for producing a paste-type electrode for a lead-acid battery according to claim 1, wherein the electrode is exposed for one hour or more in the step of exposing the electrode to an atmosphere containing carbon dioxide gas.