JPS59132566A - Forming method of cathode plate for alkaline battery - Google Patents

Abstract

PURPOSE:To decrease forming time by controlling the amount of NO3<-> ions in a plate before formation, forming current, and the amount of charging electricity for fomation in formation of a cathode plate filled with an active material by chemical impregnation. CONSTITUTION:A cathode plate 10 for an alkaline battery, which is filled with nickel hydroxide in a sintered nickel substrate by chemical impregnation, is formed with a charging bath 1 and a discharging bath 2 which are filled with an electrolyte, and equipment having a set of counter electrodes 8 and 9, rotating rollers 6 and 7, and electricity supply rollers 4 and 5. In formation, NO3<-> ions in the plate before formation is limited to 300ppm or less, forming current to 4-15C, and the amount of charging electricity for forming to 20-60% of the capacity of the plate. When forming current is large, the amount of charging electricity for forming is decreased and tension is applied to the plate. Therefore, gassing is suppressed even by increasing forming current and forming time is decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION - (A) Field of Industrial Application The present invention relates to a method for chemically forming an anode plate for an alkaline battery filled with an active material by a chemical impregnation method.

Conventional technology As a manufacturing method for sintered anode plates for alkaline storage batteries,
A chemical impregnation method is used in which a nickel sintered substrate is impregnated with an aqueous solution or molten salt of dinitrate, then neutralized in alkaline solution, and nickel hydroxide is deposited as an active material within the sintered substrate. ing. With the chemical impregnation method, it is difficult to completely remove the nitrate radicals on the electrode plate compared to the manufacturing method.In order to remove the nitrate radicals remaining in this impregnation process, the active material is activated and the charging efficiency is increased. In order to balance the charging of the anode and cathode plates after the battery is sealed by adjusting the charge within a certain range, and to avoid shrinkage of hydroxide in the pores of the sintered substrate and to facilitate the work of winding the electrode plates. Chemical formation is being carried out.

The Hutch type chemical conversion method and the continuous chemical conversion method are known as chemical conversion methods, but the continuous chemical conversion method is used from the viewpoint of workability.

This continuous chemical conversion method is carried out using a chemical conversion apparatus shown in FIG. In this drawing, 1) and (2) are a charging tank and a discharging tank, and these various types (1) and 2 are electrolytes (
3), and the power supply rollers (4) and (5) are
) is equipped with rotating rollers (6) and <7) and a pair of counter electrodes (8) and (9), respectively, and each power supply roller (4) (5) and counter electrode (8) (9) ) are each connected to a power supply. While the electrode plate (10) comes out of the unwinding part (11) and is wound up in the winding part (12), it passes through a charging tank (1) and a discharging tank (2), and a counter electrode (8) and a counter electrode (8) are formed in each tank. (9), the electrolysis is completed and the electrode plate (10) is formed or completed when it exits the discharge TL tank (2). At this time, if the electrode plate (1o) is a nickel anode, the power supply roller (4) of the charging tank (1)
) can be connected to the positive electrode of the power source, and the counter electrode (8) can be connected to the negative electrode of the power source.In the discharge tank (2), the power supply roller (5) and the counter electrode (9) can be connected to the power source in the opposite way.

Next, the amount of current to completely discharge a fully charged plate in one hour, that is, 100A for a plate with a capacity of 100A H.
Assuming that the current is IC (hereinafter C will be used as this current amount), the general chemical formation conditions are charging at 01 to 0.5 C, waiting for a time equivalent to 150 to 250% of the plate capacity, and discharging at the same rate. It uses electric current and requires 12 to 24 hours to charge and discharge. The reason why the chemical charging current is relatively small is that when charging is performed with a large current higher than that of the IC, a part of the sintered plate is peeled off from the electrode plate due to the generated gas. In order to shorten the formation time, it is possible to shorten the charging time and perform partial formation without reaching full charge, but the removal of nitrate radicals is incomplete, the flexibility of the electrode plate is insufficient, and the activity is low. There were problems such as.

(c) Purpose of the Invention The present invention was invented in view of the above points, and the formation current is increased to 4 to 15C compared to the conventional example, shortening the formation time, and gas generation due to the formation current. The purpose of this project is to provide a new chemical conversion method that regulates the amount of electricity charged in chemical conversion in order to suppress this.

(D) Structure of the Invention The present invention provides that, in the chemical formation process of an anode plate for an alkaline battery filled with an active material by a chemical impregnation method, the content of nitrate radicals in the electrode plate before formation is set to 300 ppm or less, and the formation current is set at 4 to 15C. In this method, charging and discharging is performed by setting the amount of electricity for chemical charging in the range of 20 to 60% of the capacity of the electrode plate, reducing the amount of electricity for chemical charging when the chemical current is large, and applying tensile tension to the electrode plate. ) EXAMPLE A sintered nickel substrate was impregnated with nickel hydroxide using a chemical impregnation method, and after washing with water, an electrode plate containing 38 ppm of nitrate radicals was chemically formed using the chemical conversion apparatus described in the prior art.

In addition, the capacity of this electrode plate is 0AH1 charging tank (1) per 1m.
The length of the inner tilli (8) is 2m, the discharge tank (2)
The total length of the counter electrode (9) inside is 1.2 m, and the electrolyte has a specific gravity of 1.
No. 23 strength potassium aqueous solution, total charging current of 960 A (equivalent to 6C), total discharge current of 570 A (equivalent to 6C), line speed of 40 cm/min, and tensile tension during formation in charging and discharging tanks (1) and (2). is 33±2Kg/3Q
CIT1 width, and the chemical charge electricity amount is set to 50% of the electrode plate capacity. The electrode plate thus prepared obtained the same or better effects in terms of flexibility and charging efficiency than the electrode plate prepared using the above-mentioned chemical conversion device and with a chemical conversion current of 0.2C2 and a chemical charging electricity of 150%. .

The above-mentioned electrode plate of the present invention will be explained using the drawings for comparison with a conventional electrode plate. Figure 2 shows the chemical formation conditions mentioned above.
The relationship between the amount of electricity charged during formation and the charging efficiency of the anode plate after formation was shown when the formation current was set to 0.2C, 14C, 16C and 15C, and the amount of electricity charged for formation was changed by changing the line speed. It is a drawing. still,
Charging efficiency is 0.2C in aqueous potassium solution with a specific gravity of 1.23.
The charge was charged for 2.5 hours at 0.2C, then discharged at 0.2C, and calculated using the following formula.

From this drawing, even in partial chemical formation, if charging and discharging is performed at a current more than 10 times the current of 0 and 20 used in current chemical formation,
The charging efficiency is equivalent to that of the current electrode plate, and the chemically molded d
It can be seen that the larger L becomes, the higher the charging efficiency becomes. This is because as the charging/discharging current increases, the active material in the charged state tends to remain after the completion of chemical formation.
This is thought to be because the active material does not completely discharge during large current discharge, but remains in a relatively stable form. In addition, in order to obtain a charging efficiency of 85% or more, which is higher than that of the current chemical, it is approximately 2 at 15C.
0%, approximately 40% at 6C, approximately 60% or more at 4C, and approximately 40% at 15C, approximately 55% at 6C.
%, 4C, the generation of scum starts at about 70% of the charging electricity amount for formation, so it is necessary to carry out the formation with the charging electricity amount within the above range. Next, when charging at 15c or more, gas generation started immediately after charging started, and peeling of the electrode plate surface was observed even with partial conversion of about 30%, indicating that it was a maximum conversion charging type? 15C is considered to be the limit for jC. For charging at a current of 40 or less, in order to obtain the necessary charging efficiency, it is necessary to continue charging even after gas generation has started, and partial chemical formation at a current of 40 or less is considered inappropriate.

Figure 3 shows an electrode plate that was chemically formed by changing the amount of nitrate roots before chemical formation under the above-mentioned chemical formation conditions, and the amount of nitrate roots before chemical formation was changed with a chemical formation current of 0.2C and a charging electricity amount of 150%. 2 is a drawing showing the relationship between the amount of nitrate radicals in the IIS electrode plate before chemical formation and the variation in charging and efficiency of the electrode plate which has been subjected to chemical formation. It can be seen from this drawing that as the chemical charging current increases, variations in charging efficiency occur, and that the variations clearly become larger as the amount of nitrate radicals in the electrode plate increases. Although it cannot be clearly elucidated, some current is consumed in the decomposition of nitrate roots, and this is thought to have a large effect in the case of partial metamorphosis.
Since conventional chemical conversion methods avoid overcharging, it is thought that even if a small amount of side reactions occur, the battery will be fully charged and the charging efficiency will remain constant. In this way, in the past, most of the nitrate radicals could be removed in the chemical conversion process, so there was no need for particularly strict management of water washing in the impregnation process, or in order to perform partial chemical conversion, the amount of nitrate radicals was 300 ppm as shown in the drawing. m or less, preferably 1100 pp or less.

Next, we tested the flexibility of the electrode plates. FIG. 4(a) is a drawing showing a method for determining the flexibility of an electrode plate, and the four-way stiffness measuring device includes a U-shaped fixing jig (12), a load cell (12) that supports the fixing jig from below ( 15), the fixing jig (1
2) Rotating rollers (13) attached to both ends of (13
) and C fixed jig, which is located above the bending and pressing jig (13,) and descends during one rotation at a constant speed (13,
4), the electrode plate (10) is composed of rotating rollers (13) (1
3) and the new curve pressing jig (14), and the bending pressing jig (14) is lowered to bend and measure the flexibility. Figure 4 (load cell (15)) is a diagram showing the relationship between the load on the load cell (15) and the descending distance of the new curve pressing jig (14) when the electrode plate is newly bent to a certain displacement. The maximum load of the load cell (15>) at this time is A, the descending distance of the bending pressurizing jig (14) at this time is C1, and the new song pressurizing jig (14) at the lowering limit of the new song pressurizing jig (14). The load cell load when the descending distance becomes D (fixed value) is set as B, and the above A,
The flexibility index was calculated from the values of B and C using the following formula.

Section 5 is W for the product formed under tensile tension under the above-mentioned formation conditions,゜2C1 charging electricity amount is 150
5 is a drawing showing the relationship between the amount of charge electricity and the flexibility index when the flexibility is measured using the apparatus shown in FIG. 4, where Z is the material to which no tensile tension was applied. From FIG. 5, it can be seen that when the amount of conversion is large, the flexibility increases, and when the amount of conversion is 80% or more, the flexibility becomes almost constant, and the magnitude of the conversion current does not have much effect on flexibility. It was also found that the flexibility of λ was significantly increased when chemical conversion was performed with the electrode plate under tension. Initially, this was thought to be due to the electrode plate elongating, but since the flexibility did not increase much even if the same tension was applied to the electrode plate after chemical formation, it seems that the electrode plate was not elongated and folded. As a result, even with partial chemical formation, it was possible to obtain an electrode plate that had flexibility equal to or greater than that of conventional chemical formation methods, even if the formation was not performed under tension.

(F) Effects of the Invention According to the present invention, by controlling the amount of charge electricity for formation at a formation current of 4 to 15C, which is larger than that of conventional methods,
- In addition to significantly shortening the formation time, gas generation is suppressed to prevent electrode plate peeling, and charging efficiency is equal to or higher than that of conventional methods, and when performing formation with tensile retention, Furthermore, there is an effect that an electrode plate having more flexibility than before can be obtained.

[Brief explanation of drawings]

Section 1 is a schematic diagram of the continuous chemical conversion equipment, Section 2 is a drawing showing the relationship between the amount of charge electricity for chemical conversion and charging efficiency when the chemical conversion current is varied, and Figure 3 is a diagram showing the relationship between the amount of charging electricity for chemical conversion and charging efficiency when the amount of nitrate radicals is varied. Figure 4 (a) is a drawing showing the relationship between the amount of nitrate roots and the variation in charging efficiency.
> is a drawing showing the method for measuring the flexibility of the electrode plate, Fig. 4(b)
5 is a diagram showing the relationship between the load of the load cell and the descending distance of the bending jig, and FIG. 5 is a diagram showing the relationship between the amount of charged electricity and the flexibility index depending on the presence or absence of tensile tension.

Claims (1)

[Claims] 1) In the chemical formation process of an anode plate for an Alka-11 battery filled with an active material by a chemical impregnation method, the temporary nitric acid concentration in the electrode plate before chemical formation is 300 ppm or less, and the chemical formation current is 4 to 15C. and a method for chemically forming an anode plate for an alkaline battery, which is characterized in that the amount of electricity charged in the forming charge is reduced in the range of 20 to 60% of the amount left on the electrode plate, and the amount of electricity charged in the forming charge is reduced when the forming current is large. . (2) A method for chemically forming an anode plate for an alkaline battery according to claim 1, wherein the chemically forming process is performed by applying tensile tension to the electrode plate in the surface forming process.