JPH10241746A - Charging method of sealed-type lead storage battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the life time performance of a battery for making electric power efficiency superior by making change electric quantity after discharging to have a specific range exceeding the last discharge electric quantity, and dividing the discharge current into two stages or more, regardless of the depth of an electric discharge and the size of an electric discharge current. SOLUTION: A charged electric quantity after an electric discharge in a sealed-type lead storage battery, wherein an irregular electric discharge is repeated, is made exceeding 100% and equal or less than 105% of the last discharge electric quantity, regardless of the depth of electric discharge or the size of an electric discharge current. Overcharge quantity is minimized, while the last discharge quantity can be nearly completely charged, to minimize the reduction of an electrolyte and the corrosion of an aggregate. Charge quantity at that time is divided into at least two stages or more, to change the shape of the crystal particle of an active material for ensuring the diffusion path of an electrolyte, thereby keeping subsequent discharge capacity. A charging current is gradually reduced as full charge is approached, to suppress the generation of an oxygen gas from a positive electrode, also to increase the charging efficiency of both the electrodes and it is desirable that battery temperature while charging to be controlled at 10-50 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for charging a sealed lead-acid battery.

[0002]

2. Description of the Related Art A sealed lead-acid battery characterized by the fact that maintenance of the battery such as water replenishment is not required is the largest amount of electricity required for charging up to 110% to 120% of discharge.
It has been said that if it falls below this, the capacity will gradually decrease and the life will be shortened. For that, always 10% -20%
Overcharge is performed every cycle, and the following adverse effects due to overcharge have been pointed out.

[0003] Unlike a conventional liquid battery, a sealed lead-acid battery prevents reduction of electrolyte by a reaction of reducing oxygen gas generated by electrolysis of water at the positive electrode to water at the negative electrode during overcharge. I have. However, in reality, the efficiency of reducing oxygen gas to water in this sealed lead-acid battery is not completely 100%, and therefore, it is known that the amount of electrolyte inside the battery decreases as the overcharge amount increases. Have been. Such a decrease in the electrolytic solution causes an increase in the concentration of sulfuric acid in the electrolytic solution and an increase in the internal resistance, thereby shortening the cycle life of the battery.

Further, when the lead storage battery is overcharged, the lead alloy used for the current collector (or grid) of the positive electrode corrodes and changes to lead dioxide, so that the conductivity and the conductivity of the current collector are reduced. A decrease in strength, deformation from the initial shape, or the like occurs, which is also a major cause of shortening the cycle life of the battery. Until now, in order to suppress the corrosion of the current collector due to this overcharging, improvements in composition such as adding tin to the alloy have been made, and the effect of extending the life has been obtained. It was not enough to achieve the extension.

In order to solve the problem of overcharging of the sealed lead-acid battery, in recent years, as described in Japanese Patent Application Laid-Open No. Hei. It has been proposed to reduce the amount of overcharge, suppress both the reduction of the electrolyte and the corrosion of the current collector and extend the cycle life. However, in this method, since the battery is not completely charged with respect to the discharge amount during a normal cycle, the active material in the electrode plate, in particular, the large crystalline lead sulfate that is difficult to be reduced by the charge in the negative electrode active material is formed. It is difficult to grow, and overcharging is required once every few cycles to suppress the above-mentioned phenomena.Therefore, the life of the battery depends on the frequency, and the charging system and pattern become complicated. Was.

Further, as a feature of the lead storage battery, at the time of overcharging, the power of the battery (Wh = charging current × battery voltage) increases because the voltage of the battery rises greatly,
There is also a problem that power efficiency (discharge power / charge power) deteriorates.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for charging a sealed lead-acid battery which has improved power-efficiency while improving the life performance of the sealed lead-acid battery. Is to provide.

[0008]

SUMMARY OF THE INVENTION The present invention is to improve the life performance of a sealed lead-acid battery by controlling its charging method without deteriorating the performance of the battery. Irrespective of the depth of discharge and the magnitude of discharge current, it should be more than 100% of the amount of previous discharge and not more than 105%, the charge current should be divided into at least two stages, and the charge current should be close to full charge. And charging the battery during charging / discharging to a temperature of 10 ° C. or more and 50 ° C. or less.

[0009]

In a sealed lead-acid battery for use in cycle services, which is used as a power source for electric vehicles and road leveling, controlling the charging method after discharging is an indispensable element for improving its life performance. One. Further, since such a battery for cycle service is used according to the convenience of the user, the magnitude of the discharge current and the depth of discharge are not always constant.

[0010] The amount of charged electricity of a sealed lead-acid battery for cycle service in which such irregular discharge is repeated is 100% of the previously discharged amount of electricity regardless of the depth of discharge and the magnitude of discharge current. To 105% or less to minimize the amount of electrolyte and the corrosion of the current collector by minimizing the amount of overcharge while charging the previously discharged amount almost completely. By repeating such charging, the life performance of the sealed lead-acid battery is improved.

At this time, the charge current is divided into at least two or more steps to change the shape of the crystal grains of the active material, secure a diffusion path for the electrolyte, and maintain a discharge capacity afterward. By gradually decreasing the charging current as the distance approaches, the generation of oxygen gas from the positive electrode is suppressed, the charging efficiency of both electrodes is increased, and the life performance and discharge performance of the sealed lead-acid battery are improved.

In addition, by performing these charging methods, power loss due to overcharging can be suppressed, so that power efficiency during charging and discharging can be improved.

Further, when the battery temperature is lower than 10 ° C., the easiness of charging the active material is extremely reduced, so that the battery is apt to be insufficiently charged. The self-discharge rate is extremely increased to cause insufficient charging and the corrosion rate of the current collector increases. Therefore, these phenomena can be suppressed by controlling the battery temperature to 10 ° C. or more and 50 ° C. or less.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION

(Example 1) A closed paste type lead-acid storage battery of the 12V type having a nominal capacity of 30 Ah for 3 hours was assembled and charged and discharged at a temperature of 25 ° C under the conditions shown in Table 1.

FIG. 1 shows the test results. The numbers in the figure indicate the numbers of the conditions in Table 1.

[0016]

[Table 1]

Assuming that the life is at the time when the three-hour rate capacity of the battery becomes 80% or less of the initial capacity, under the conditions 1 and 2 in which the absolute amount of charge is insufficient, 30 and 50 respectively.
Under the conditions 9 and 10, which are referred to as normal charging conditions, the life was about 200 cycles, whereas the amount of charge in conditions 4 to 7 was 10%.
Approximately 400 to 60 under the condition of more than 0% and 105% or less
The life reached 0 cycles. The condition 3 where the amount of discharged electricity = the amount of charged electricity has a better life transition than the conditions 1 and 2, and the life is 140 cycles. The condition 8 where the amount of charged electricity is about 106% is about 300 cycles. Life has expired.

For these batteries, after the test was completed, the amount of decrease in the electrolyte by weight measurement of the battery was 0.01% / cycle to 0.1% of the initial amount of the electrolyte under conditions 1 to 7.
While there was almost no difference at 02% / cycle, there was a sharp increase to 0.04% / cycle under Condition 8, and 0.08% / cycle under Conditions 9 and 10.

After disassembly, the cause of the life of these batteries was examined. As a result, under conditions 1 to 3, corrosion of the current collector of the positive electrode was scarcely observed. A certain amount of lead sulfate was detected in a large amount of 30% to 80%, and in particular, the lead sulfate crystal of the negative electrode was coarsened to cause so-called sulfation. Further, under conditions 8 to 10, almost no sulfation of the negative electrode as described above was observed, but the current collector of the positive electrode corroded, and more than half of its volume was converted to lead dioxide, resulting in reduced strength and conductivity. Its function had been reduced. In Conditions 4 to 7, the cause of the life was lead sulfate formation of the negative electrode active material, but the amount was as small as 30% or less, and the crystal size was smaller than in Conditions 1 to 3. Further, the corrosion of the current collector of the positive electrode is also advanced from the condition 1 to the condition 3, but considering that the function of the current collector has been reduced in about 200 cycles so far, the corrosion rate is sufficiently high. It was found that it was suppressed.

From these facts, when the amount of charged electricity is more than 100% and not more than 105% of the amount of discharged electricity, the decrease of the electrolyte, the sulfation of the negative electrode and the corrosion of the positive electrode current collector are suppressed at the same time. It has been found that the cycle life of the sealed lead-acid battery can be extended by two to three times.

Further, while the power efficiency in the conditions 9 and 10 with a large overcharge is 70% to 75%, the power efficiency in the conditions 4 to 7 where the overcharge is small is from 75% to 85%. It was found that high charging and discharging power efficiency was obtained.

Example 2 A battery having exactly the same specifications as in Example 1 was assembled and charged and discharged at a temperature of 25 ° C. under the conditions shown in Table 2.

FIG. 2 shows the test results. The numbers in the figure indicate the numbers of the conditions in Table 2.

[0024]

[Table 2]

Assuming that the life is at the time when the three-hour rate capacity of the battery becomes 80% or less of the initial capacity, the amount of charged electricity is 103.1% of the amount of discharged electricity. By changing the current stepwise, up to 100
The cycle life can be extended. As a result of disassembling these batteries, it was found that in the batteries in which the current was changed stepwise, the active materials of both electrodes did not have a uniform particle size, but changed to various large and small crystal diameters. It is considered that such a crystal morphology guarantees a diffusion path of the electrolytic solution at the time of the next discharge, so that it is possible to secure a capacity particularly at the end of life. Therefore, the same effect can be obtained in charging such that the stepwise change of current is performed in a time as short as possible, that is, in charging by pulse current.

Further, the stepwise change of the current is the condition 6-1.
It was found that, as in conditions 6-2 and 6-5, the effect of extending the life was prominent when the value was reduced toward the end of charging. It is considered that this is largely due to the above-described effects and an increase in the charging efficiency of the active material due to the small current. The positive electrode of a lead-acid battery is charged with the generation of oxygen gas from around 80% of the full charge with the generation of oxygen gas. However, the generated oxygen gas naturally reacts at the negative electrode, so that the charging efficiency of the negative electrode also decreases. . In the charging method in which the amount of overcharge electricity is 5% or less as in this example, it is considered that the reaction of the negative electrode with oxygen eventually promotes the sulfation of the negative electrode. Reducing the charging current as it approaches full charge can increase the charge efficiency of the positive electrode near full charge, suppress the generation of oxygen gas, and eventually increase the charge efficiency of the negative electrode. In such a charging method with a small amount of overcharge electricity, the effect is more exhibited.

As for the power efficiency, all of these charging methods also exhibit an efficiency of 75% to 90%. Particularly, the method of reducing the current at the end of charging has a high power because both the current and the battery voltage are small. It turns out that efficiency can be obtained.

(Example 3) Further, a plurality of batteries having exactly the same specifications as those in Example 1 were assembled, and the discharge conditions were set to 10 A x 2 hours and the charge conditions were set to the first stage while maintaining the respective battery temperatures under the conditions shown in Table 3. Is 10A x 1 hour and 36 minutes, the second stage is 1.5A x
Two-stage constant current charging for 3 hours and 4 minutes (103% of discharged electricity)
A cycle test was performed.

[0029]

[Table 3]

FIG. 3 shows the results of carrying out a capacity test of these batteries A to J at a rate of 3 hours at 25 ° C. every several cycles. However, FIG. 3 does not show the transition of each of the batteries A to J, and indicates that the battery temperature is −10 ° C. to 10 ° C., 10 ° C. to 50 ° C., 50 ° C.
Those included in the range of 80 ° C. are collectively shown. From FIG. 3, the three-hour rate capacity of the batteries A to J is 80% of the initial capacity.
Assuming that the service life is reached at the time when the battery life becomes below, any of the charging methods is a two-stage charge of 103% with respect to the amount of discharged electricity.
0 ° C to 10 ° C and 50 ° C to 80 ° C batteries are 10 ° C
It was found that the battery life was shorter than that of the battery at ５０50 ° C.

Further, a plurality of batteries having exactly the same specifications as those of Example 1 were assembled, and a cycle test was performed under the same conditions as those of the batteries A to J while maintaining the battery temperature of each battery under the conditions shown in Table 4. FIG. 4 shows the results. FIG. 4 also shows battery temperatures of 10 ° C. to 25 ° C., 25 ° C. to 35 ° C., and 35 ° C.
The cycle characteristics are collectively shown for each battery included in the range of ° C.

[0032]

[Table 4]

From the test results, it was found that the battery temperature was 10 ° C. to 5 ° C.
It was found that the life was longer when the temperature was controlled in the range of 0 ° C., especially in the range of 25 ° C. to 35 ° C.

Next, these batteries were disassembled and investigated. As a result, the batteries charged and discharged with the battery temperature controlled within the range of -10 ° C. to 10 ° C. were converted to lead sulfate of the active material, particularly, the sulfation of the negative electrode. The battery was charged and discharged at a temperature of 50 ° C. to 80 ° C. due to lead sulfate of the positive electrode active material and corrosion of the current collector.

Further, regarding the power efficiency, 10 ° C. to 5 ° C.
The battery at 0 ° C. exhibited an efficiency of 80 to 90%, indicating that high power efficiency was obtained.

The effects described in the first to third embodiments are as follows.
In addition to the sealed lead-acid batteries used in the experiment, the size of the capacity and the type of the sealed lead-acid batteries, such as the type of current collector, such as a cast grid or expanded grid, gel type or other electrolytic solution holding method, etc. Regardless, it was obtained similarly.

[0037]

As described above, according to the present invention, the following effects can be obtained.

(1) According to the first aspect, the life performance of the sealed lead-acid battery can be improved without changing the structure or configuration of the sealed lead-acid battery and by only controlling the charging method without impairing the performance of the sealed lead-acid battery. Power loss due to the charge and discharge of the battery.

(2) According to the second aspect, the charging efficiency of the positive electrode and the negative electrode can be increased, the amount of overcharged electricity can be reduced, and the life performance of the sealed lead-acid battery can be improved.

(3) According to the third aspect, the effect of the above (2) can be remarkable.

(4) According to the fourth aspect, insufficient charging and an increase in the corrosion rate of the current collector can be prevented, and the life performance of the sealed lead battery can be improved.

[Brief description of the drawings]

FIG. 1 is a graph showing a transition of a three-hour rate capacity when a discharge current and a discharge time are constant and a charge amount is changed under a condition of a constant charge current.

FIG. 2 shows a condition where a discharge current and a charge amount are constant.
It is the graph which showed transition of three hour rate capacity when changing charging current and time.

FIG. 3 shows a battery temperature of −10 ° C. to 10 ° C. and 10 ° C. to 50 ° C.
4 is a graph showing a change in capacity for 3 hours when a battery is subjected to a charge / discharge test by the method of the present invention while controlling to a constant value within a range of 50 ° C. to 50 ° C. to 80 ° C.

FIG. 4 shows battery temperatures of 10 ° C. to 25 ° C., 25 ° C. to 35 ° C.,
5 is a graph showing a transition of a three-hour capacity when a battery is subjected to a charge / discharge test by a method of the present invention while controlling the battery to a constant value in a range of 35 ° C. to 50 ° C.

Claims (4)

[Claims] 1. In a sealed lead-acid battery for use in cycle services in which irregular discharge is repeated, the amount of charged electricity after discharging is determined to be 100% of the previously discharged amount of electricity irrespective of the depth of discharge and the magnitude of discharge current. A method for charging a sealed lead-acid battery, characterized by exceeding 105% and not more than 105%. 2. The charging method according to claim 1, wherein
A method for charging a sealed lead-acid battery, wherein the charging current is divided into at least two or more stages. 3. The charging method according to claim 1, wherein
A method for charging a sealed lead-acid battery, characterized in that the charging current is gradually reduced as the battery approaches full charge. 4. The battery temperature during charging and discharging is 10 ° C. or more and 50 ° C.
The method for charging a sealed lead-acid battery according to any one of claims 1 to 3, wherein: