JP2001028263A - Lead-acid battery formation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently conduct formation, even at high specific gravity formation with low efficiency and increase low rate discharge capacity and high rate discharge capacity by keeping electrolyte temperature during current supply in a specified range, and increasing the quantity of supply electricity for formation to specified times the theoretical capacity of a positive electrode active material. SOLUTION: Electrolyte temperature during current supply is kept at 50-70 deg.C, and the quantity of supply electricity is made 150-250% that of the theoretical capacity of a positive electrode active material in the formation of a lead-acid battery. The total current supply time for formation, or the time kept at high temperature is preferably at most 10 hours, and thereby, even in the lead-acid battery in which the weight ratio of a negative electrode active material to the positive electrode active material is 0.5 or more but less than 1.0, battery formation can surely be conducted. When an organic additives, for example, a natural polymer such as lignin or its derivative, or a synthetic organic material is contained in a negative electrode plate, the decomposition of these materials is retarded, the drop in discharge performance of the negative electrode is prevented, and a lead-acid battery with good high rate discharge performance can be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for forming a lead storage battery.

[0002]

2. Description of the Related Art Lead storage batteries can be roughly classified into the following two types. A method in which dilute sulfuric acid, which is an electrolytic solution having a low specific gravity [specific gravity of 1.1 (converted to 20 ° C.), and thereafter, the specific gravity is all converted to 20 ° C.), is supplied with electricity, and then the liquid is changed to a predetermined specific gravity (low specific gravity). Chemical formation), and at first a relatively high specific gravity (specific gravity 1.
2) is a method (high specific gravity formation) in which an electrolytic solution is supplied and energized to obtain a specific gravity as it is. In the high specific gravity formation, the formation is not completed unless an excessive amount of electricity is supplied because the formation efficiency is poor. Low-density chemical conversion requires only a small amount of electricity due to excellent formation efficiency, but requires large equipment for electrolyte exchange. On the other hand, the following problems have occurred. Generally, the amount of the negative electrode active material of the conventional lead battery is designed to be substantially equal to or more than the amount of the positive electrode active material.
This was done so that the negative electrode active material had a margin so that the positive electrode plate became a life-limiting factor. However, recently, the demand for improving the energy density of the battery has increased, and the number of the batteries in which the amount of the negative electrode active material has been reduced and the amount of the positive electrode active material has been increased accordingly has increased. This is because the utilization rate of the negative electrode active material is higher than that of the positive electrode active material, and thus the positive electrode active material becomes a capacity limiting factor. However, the ratio of the amount of the negative electrode active material to the amount of the positive electrode active material is at least about 0.5. This is because below this, the negative electrode becomes a capacity limiting factor. In such a battery, since the positive electrode and the negative electrode are not balanced, either the high specific gravity or the low specific gravity conversion method does not work, and the battery capacity may be insufficient. This is due to the following reasons. When the formation of the negative electrode plate is completed, hydrogen generation starts, and the polarization rapidly increases. In a battery in which the amount of the negative electrode active material is smaller than that of the positive electrode active material, the completion of formation is earlier than in a normal battery, so that the start of polarization is earlier. As a result, the time during which the battery is left in a large polarization state until the end of the energization becomes longer than that of a normal battery. An organic additive is generally used in the negative electrode active material to prevent shrinkage, and when the organic additive is placed at a hydrogen generation potential, it decomposes and elutes to a remarkable decrease, and the organic additive in the negative electrode active material is reduced. The amount of the organic additive present in the negative electrode plate is smaller than that in a normal battery, and the contraction of the negative electrode plate is increased. The shrinkage of the negative electrode plate causes a decrease in the high-rate discharge capacity because the high-rate discharge performance is limited to the negative electrode. Then, the formation of the positive electrode becomes insufficient and the low-rate discharge capacity decreases.

[0003]

SUMMARY OF THE INVENTION In view of the above, the present invention enables a high-rate chemical conversion to be performed even in a high-density chemical conversion with low formation efficiency, and provides a sufficient low-rate discharge capacity and high-rate discharge capacity. It is another object of the present invention to provide a chemical conversion method for a lead storage battery, which is capable of reliably forming even a battery in which the amount of the negative electrode active material is smaller than the amount of the positive electrode active material. I do.

[0004]

According to the method for forming a lead storage battery of the present invention, the temperature of the electrolyte during energization is maintained at 50 to 70 ° C.
It is characterized in that the amount of electricity to be supplied is set to 150 to 250% of the theoretical capacity of the positive electrode active material, and can be suitably used, for example, in case of carrying out battery formation.

In general, as the amount of electricity decreases, the chemical nature of the positive electrode plate deteriorates. However, by performing the chemical formation by such a method in which the temperature and the amount of supplied electricity are optimized, the formation efficiency of the positive electrode plate can be improved. Thus, the formation efficiency of the lead storage battery can be improved as a whole.

The energizing time for the above-mentioned chemical conversion is appropriately set, but the total energizing time (that is, the time during which the battery is kept at a high temperature) is preferably 10 hours or less. When an additive, for example, a natural polymer such as lignin or a derivative thereof or a synthetic organic substance such as a naphthalene-based compound, is contained in the negative electrode plate, the decomposition of the additive is suppressed, and a decrease in the discharge performance of the negative electrode is prevented. As a result, a lead-acid battery having excellent high-rate discharge performance can be manufactured.

[0007] The above-mentioned chemical conversion method is characterized in that a negative electrode potential tends to reach a hydrogen generation potential more quickly, and a lead such that the weight ratio of the negative electrode active material to the positive electrode active material is 0.5 or more and less than 1.0. It is particularly suitable as a method of forming a storage battery. Such a formation method, in particular, a method in which the total energization time is set to 10 hours or less, makes it possible to form a positive electrode active material which has not been successfully formed in any of high specific gravity and low specific gravity. A lead storage battery in which the weight ratio of the negative electrode active material is 0.5 or more and less than 1.0 can be more reliably formed.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be further described with reference to specific examples. (Specific Example 1) The relationship between the formation efficiency of the positive electrode plate and the temperature is shown below. A test cell containing one positive electrode plate and two negative electrode plates was used. The test conditions are shown below. Electrode plate: unformed positive electrode plate (theoretical capacity: 10 Ah) Sulfuric acid: specific gravity 1.20 Electric current: 2 A Electric current: 10 to 25 Ah (100 to 25 of theoretical capacity)
0%) Electrolyte temperature: 20 to 100 ° C. FIG. 1 is a diagram showing the relationship between the formation efficiency and the temperature of the positive electrode plate with the amount of generated PbO _{2 on} the vertical axis and the electrolyte temperature on the horizontal axis. From the figure, in the range below 50 ° C., the amount of PbO ₂ generated increases as the amount of electricity supplied increases, and at 50 to 70 ° C.
It can be seen that the amount of generated PbO ₂ is large, and the difference depending on the amount of energized electricity is small. On the other hand, it can be seen that when the temperature exceeds 70 ° C., the production amount is greatly reduced, and even when the temperature is increased, the formation efficiency of the positive electrode plate is not necessarily improved. This is probably because the amount of oxygen generated as a side reaction increased and the active material dropped off at high temperature. From these results, it can be seen that in order to increase the formation efficiency of the positive electrode plate, the temperature should be in the range of 50 to 70 ° C., and the amount of charged electricity should be 150% or more. In addition, even if the charged amount of electricity is 250% or more, PbO ₂
Since there is no change in the generation amount of, it is better to set the efficiency to 250% or less. (Specific Example 2) Reduction of organic additive in negative electrode active material and temperature,
The relationship with time is shown below.

FIG. 2 shows the amount of the organic additive remaining in the negative electrode active material when the negative electrode plate was left in sulfuric acid and the temperature was changed. The test was performed under the following conditions.

Electrode plate: chemically converted negative electrode plate Organic additive: sodium ligninsulfonate, 0.5% by weight added to negative electrode active material Sulfuric acid: specific gravity 1.28 As can be seen from FIG. In the following, the decrease in organic additives was small even when the standing period was prolonged.
In the case of 70 ° C., the decrease increased from beyond 10 h. At 80 ° C., the decrease was large immediately after the start of standing.
From this result, it is understood that the leaving temperature should be at most 70 ° C., and even in that case, the leaving should not be performed for more than 10 hours.

(Example 3) Next, an example in which the effect of the present invention was applied to a battery and confirmed was described.

As the battery, an automotive battery (55D23,
12V, 48Ah / 5hR) was prepared and tested.
This battery uses an expanded grid made of a Pb-Ca-Sn-based alloy for both the positive grid and the negative grid. The alloy composition of the rolled lead alloy sheet used for the expanded lattice of the positive electrode is Pb-0.06 wt% Ca-1.5 wt% Sn, and the alloy composition of the sheet for the negative electrode is Pb-0.06 wt% Ca-
0.5 wt% Sn. Each was prepared by a rolling method, and the thickness was 1.1 mm for the positive electrode and 0.6 m for the negative electrode.
m. These rolled sheets were developed and cut by a rotary expanding machine to produce a lattice. The expanded grid was filled with a general paste for automotive lead-acid batteries, and aged in a usual manner to produce a positive electrode plate. As the negative electrode plate, a general one containing sodium ligninsulfonate as an organic additive was used. The amount of the positive electrode active material per cell was equivalent to 96 Ah in theoretical value. Regarding the amount of the negative electrode active material, 0.8 and 1.1 were prepared for the positive electrode active material.

Next, the positive electrode plate was placed in a bag-shaped microporous polyethylene separator. Ribs are formed on the inner side, which is the surface in contact with the positive electrode plate. In this case, the positive electrode plate is placed in the bag-shaped separator, but the negative electrode plate may be placed in such a case so that the ribs are on the outside.

[0014] Five positive plates and six negative plates placed in a separator
The elements were alternately overlapped to form an element, and the six elements were inserted into a battery case, then connected between cells, and the lid was welded to obtain a battery.

For these batteries, a battery case was formed in the following procedure. 1. 1. Inject electrolyte sulfuric acid into battery Set the batteries in the aquarium. Terminal connection.

Since the amount of heat generated during the formation varies depending on the magnitude of the flowing current, the correlation between the flowing current value and the temperature of the electrolytic solution is examined in advance in a preliminary test. The water bath temperature was adjusted to be as follows. 3. Leave until the electrolyte has spread inside the electrode plate. This time 1h
And 4. Energization 5. Termination of energization As test factors, (A) electrolyte temperature, (B) energization amount, and (C) energization time were examined. The battery after the formation was subjected to a low rate discharge test (25 ° C., 9.6 A discharge, cutoff voltage 1).
0.2 V) and a high-rate discharge test (−15 ° C., 300 A discharge, final voltage 6.0 V) to investigate the performance.

Test conditions and test results for each factor are shown. Test (A) Negative electrode / positive electrode active material ratio: 0.8, 1.1 Injection specific gravity: 1.20 Electrolyte temperature: 30 to 80 ° C Electricity of electricity: 200% (positive electrode active material theoretical capacity ratio) : 8h The relationship between the low-rate discharge capacity and the high-rate discharge capacity and the electrolyte temperature is shown in FIGS. The low-rate discharge capacity shows almost the same tendency even when the active material ratio is changed because the positive electrode active material is a capacity limiting factor. A large battery was obtained. In addition, in both cases, 50 ° C.
The capacity reached the maximum in the region of 70 ° C. On the other hand, since the capacity of the high-rate discharge capacity is limited by the negative electrode active material, the capacity of 1.1 having a large amount of the negative electrode active material was slightly larger. In addition, the capacity decreases as the temperature increases, and decreases rapidly at 70 ° C. or higher. However, although the capacity was slightly reduced in a battery having an active material ratio of 0.8, the level was not a problem at an electrolyte temperature of 70 ° C. or lower. From these results, it was found that the electrolyte temperature is desirably 50 to 70 ° C. in consideration of the low rate discharge capacity, and 70 ° C. or less in consideration of the high rate discharge capacity. Test (B) Negative electrode / positive electrode active material ratio: 0.8, 1.1 Injection specific gravity: 1.20 Electrolyte temperature: 60 ° C. Electricity of electricity: 100 to 300% (positive electrode active material theoretical capacity ratio) : 8h The relationship between the low rate discharge capacity and the high rate discharge capacity and the amount of energized electricity is shown in FIGS. The low rate discharge capacity showed almost the same tendency even when the active material ratio was changed. The capacity reached the maximum in the region of 150% or more and was saturated. On the other hand, the high-rate discharge capacity reached the maximum at 150 to 250%, and the capacity decreased at higher values. The degree of the capacity decrease was larger at the active material ratio of 0.8. But it was not at a problematic level. From this result, it is understood that it is desirable that the amount of formed electricity be 150 to 250%. Test (C) Negative electrode / positive electrode active material ratio: 0.8, 1.1 Injection specific gravity: 1.20 Electrolyte temperature: 60 ° C. Electricity of electricity: 200% (positive electrode active material theoretical capacity ratio) Current application time: 5 7 to 8 show the relationship between the low-rate discharge capacity and the high-rate discharge capacity and the energizing time, respectively, in FIGS. The low rate discharge capacity showed almost the same tendency even when the active material ratio was changed. The effect of the energization time was hardly observed. On the other hand, when the active material ratio is 0.8, the high-rate discharge capacity hardly changes at 10 h or less, but starts to decrease in the region of 10 h or more. Active material ratio 1.1
Then the effect of time was small. It is understood that the energization time is desirably 10 hours or less. In the above specific examples, tests were performed with the electrolyte temperature accurately controlled in order to clarify the effects. It is possible to consider a method of bringing the temperature to a predetermined temperature range by the heat generated by this, which is more advantageous in terms of energy. In this case, the slight time during the initial temperature rise will fall outside the scope of the present invention, but can be considered substantially the same as the present invention. In addition, it is conceivable to open and close the supplied current for controlling the temperature of the electrolytic solution, or to change the current value. Not out of the ordinary.

[0018]

According to the chemical conversion method of the present invention, it is possible to increase the chemical conversion efficiency and to obtain a lead storage battery having excellent low rate and high rate discharge capacity. Furthermore, a satisfactory capacity can be obtained even in a battery in which the amount of the negative electrode active material is smaller than the amount of the positive electrode active material. In addition, by combining each of the positive electrode and the negative electrode so as to be optimal, it becomes possible to manufacture a battery having a sufficiently low discharge capacity and a high discharge capacity.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between the electrolyte temperature of a positive electrode plate and the formation efficiency.

FIG. 2 is a graph showing a relationship between a standing time and a residual amount of an organic additive in a negative electrode active material.

FIG. 3 is a diagram showing a relationship between a low rate discharge capacity and an electrolyte temperature.

FIG. 4 is a diagram showing a relationship between a high rate discharge capacity and an electrolyte solution temperature.

FIG. 5 is a diagram showing a relationship between a low-rate discharge capacity and an amount of supplied electricity.

FIG. 6 is a diagram showing a relationship between a high-rate discharge capacity and an amount of supplied electricity.

FIG. 7 is a diagram showing a relationship between a low-rate discharge capacity and a conduction time.

FIG. 8 is a diagram showing a relationship between a high-rate discharge capacity and an energization time.

Claims (3)

[Claims] 1. A method for forming a lead storage battery, wherein the temperature of an electrolyte during energization is maintained at 50 to 70 ° C., and the amount of energized electricity is 150 to 250% of the theoretical capacity of the positive electrode active material. How to form lead storage batteries. 2. The method for forming a lead storage battery according to claim 1, wherein a total energization time in said energization is 10 hours or less. 3. The battery case for a lead storage battery according to claim 1, wherein the weight ratio of the negative electrode active material to the positive electrode active material is 0.5 or more and less than 1.0. Method.