JP2814524B2 - Lead storage battery - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a lead storage battery used for starting an engine of an automobile, and a lead storage battery such as a sealed lead storage battery used for portable equipment, disaster prevention and the like.

2. Description of the Related Art Conventionally, when a lead-acid battery of this type is left for a long time in a discharged state after being used, or left in an over-discharged state due to forgetting to switch off, the internal impedance increases.
If it is attempted to charge such a battery again, in the voltage-controlled charging system, the control voltage is likely to be reached, and the charge acceptability is poor. In particular, the effect is large during short-time charging, and improvement in charge acceptability has been desired.

In such a conventional configuration, for example, in the case of a battery for a portable video movie or the like, it is demanded that a dedicated charger completes charging in about 1.5 to 2.0 hours, and an overcharge prevention mechanism is required. As a certain time after reaching the control voltage,
Some circuits are provided with a circuit for switching to an extremely small current, and a battery with poor charge acceptability may not be able to be fully charged.

The present invention solves such a problem, and aims to improve the charge acceptability of the battery itself after being left in overdischarge, and to complete charging in a short time after being left in overdischarge, regardless of the improvement of the charger. It supplies batteries.

Means the present invention for solving the problems is characterized in that the perfluoroalkyl sulfonic acid salts represented by _{C n F 2n + 1 SO 3} M in the electrolyte are contained. In particular, this M is an ammonium salt,
It is preferably any of a sodium salt, a potassium salt, and a lithium salt.

Function In a lead-acid battery, lead sulfate is generated on the positive and negative electrode plates during discharge. Since the lead sulfate itself has not only conductivity but also poor wettability, the current density at the time of charging is extremely reduced.

In the case of a sulfuric acid electrolyte in a battery, even if a surfactant composed of perfluoroalkyl sulfonate is contained in the electrolyte, which is relatively stable even in the presence of a strong oxidizing agent such as lead dioxide, lead sulfate is used. And the interfacial tension of the electrolytic solution is lowered, and the electrolytic solution enters between the crystals of lead sulfate which have poor wettability as it is, thereby reducing the current density at the time of charging and improving the charge acceptability after overdischarge standing.

The present invention reduces the interfacial tension between the electrolytic solution and lead sulfate by including a perfluoroalkyl sulfonate surfactant in the lead storage battery. That is, by this operation, it is possible to improve the charge acceptability after leaving the lead storage battery in overdischarge. Therefore, even in a battery that has been left in an overdischarged state, charging can be completed in the same charging time as immediately after discharging.

Examples Hereinafter, examples of the present invention will be described.

A positive / negative electrode plate and a separator made of fine glass fiber were combined to produce a sealed lead-acid battery with a voltage of 12 V and a 10-hour rate capacity of 2 Ah. Dilute sulfuric acid having a specific gravity of 1.32 was used as the electrolyte.
C ₈ F ₁₇ SO ₃ NH ₄ (ammonium perfluorooctane sulfonate), C ₈ F ₁₇ SO ₃ Li (lithium perfluorooctane sulfonate), C ₆ F ₁₃ SO ₃ Na (perfluorohexane) Sodium sulfonate), C ₈ F ₁₇ SO ₃ K (potassium perfluorooctane sulfonate), C ₈ F ₁₇ SO ₃
Using H (perfluorooctanesulfonic acid) as a surfactant, 1 × 10 ⁻⁵ , 1 × 10 ⁻⁴ , 1 × 10 ⁻³ ,
1 × 10 ^-2 and 1 wt% were added. Of these, C ₈ F ₁₇ SO ₃ NH ₄
Did not melt at 1 wt%, so 0.5 wt% was added.

Using the battery prepared as described above and a battery prepared without adding a surfactant for comparison, the charge acceptability after being left in overdischarge was tested. First, the test was performed after the battery was fully charged at 0.1 CA, but the test was stopped because the foam overflowed from the exhaust port at the addition of 1 wt% and 0.5 wt%, respectively. Perform a constant resistance discharge equivalent to 0.75 A at 25 ° C for 24 hours with other materials, and then leave it at 25 ° C for one month,
Fig. 1 shows the inrush current when charging by the constant voltage constant current method of 14.8V / 1.6A and the time required to reach 1.6A. In this figure, the one located at the lower right has excellent charge acceptability.

FIG. 2 shows the amount of electricity charged when the charging is completed in 2 hours.

As is clear from FIGS. 1 and 2, the rush current increases and the time to reach 1.6 A is shortened by addition. If the inrush current is high and the time to reach 1.6 A is short, the amount of charged electricity is large. Fig. 3 shows C ₈ F ₁₇ SO ₃ NH ₄ with 1 × 10 ^-3 wt
5 shows changes in current during constant-voltage charging of a sample with% addition and a sample without% addition.

Also, if the amount is small, the effect will not be seen,
Also, the perfluoroalkyl sulfonate is relatively insoluble in sulfuric acid, and even if it is soluble, if the amount of addition is increased, bubbles generated when gas is generated during charging will not disappear,
It is not preferable because it overflows from the exhaust port. Further, the effects of ammonium salts, sodium salts, potassium salts and lithium salts are higher than those of perfluoroalkylsulfonic acid at the same addition concentration.

Effects of the Invention As described above, according to the present invention, it is possible to supply a lead storage battery having improved charge acceptability after being left in overdischarge.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between the rush current after overdischarge standing and the time until the maximum current is reached, FIG. 2 is a diagram showing the relationship between the amount of added surfactant and the amount of charged electricity, and FIG. 3 is a diagram showing the addition of surfactant. FIG. 10 is a current characteristic diagram at the time of constant-voltage charging of the device.

Claims (3)

(57) [Claims] 1. A lead-acid battery containing a perfluoroalkyl sulfonate represented by C _n F _{2n + 1} SO ₃ M in an electrolytic solution. 2. The lead-acid battery according to claim 1, wherein M of C _n F _{2n + 1} SO ₃ M is any one of an ammonium salt, a sodium salt, a potassium salt, and a lithium salt. . 3. The lead-acid battery according to claim 1, wherein the electrolyte contains 1 × 10 ⁻⁴ to 1 × 10 ⁻² wt% of perfluoroalkyl sulfonate.