JPH02236968A - Lead-acid battery - Google Patents

Abstract

PURPOSE:To increase the charge acceptability of a battery allowed to stand after overdischarge by containing a perfluoroalkylamine oxide surface active agent represented by CnF2n+1CONH(CH2)3N<+>(CH3)3I<->. CONSTITUTION:A perfluoroalkylamine oxide surface active agent represented by CnF2n+1CONH(CH2)3N<+>(CH3)3I<-> is contained in a battery. Its content is 1X10<-4>-1X10<-2>wt%. Surface tension between lead sulfate and an electrolyte is reduced and the electrolyte penetrates into between crystals of lead sulfate having bad wettability to decrease charging current density. The charge acceptability of the battery allowed to stand after overdischarge is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to lead-acid batteries such as lead-acid batteries used for starting automobile engines, and sealed lead-acid batteries used for portable equipment, disaster prevention, and the like.

BACKGROUND OF THE INVENTION If a lead-acid battery of this kind is left in a discharged state for a long period of time after use, or if it is left in an over-discharged state due to forgetting to turn off the switch, the internal impedance increases. When attempting to charge such a battery again, in a voltage-controlled charging method, the control voltage is easily reached, resulting in poor charge acceptance. This effect is particularly large during short-time charging, and it has been desired to improve charging acceptability.

Problems to be Solved by the Invention With the conventional configuration as described above, for example, batteries for portable video movies can be used for 1.6 to 2.5 hours using a dedicated charger.
There is a demand for charging to be completed in about 0 hours, and some devices are equipped with a circuit that switches to a very small current after a certain period of time after reaching the control voltage as an overcharging prevention mechanism. Batteries with poor receptivity sometimes did not reach a fully charged state.

The present invention solves these problems by improving the charging acceptability of the battery itself after being left over-discharged, without improving the charger, so that charging can be completed in a short time even after being left over-discharged. It supplies batteries.

Means for Solving the Problems In order to solve the above problems, the present invention uses lead acid ■
e CnF2n+, CONH(OH2), N (
It is characterized by containing a perfluoroalkylamine oxide surfactant represented by CH,)3I.

In working lead-acid batteries, lead sulfate is produced on the positive and negative plates during discharge. Is this lead sulfate itself not conductive?
Since the wettability is poor, the current density during charging is made very low.

It is relatively stable even in the sulfuric acid acidic electrolyte in the battery and in the presence of a strong oxidizing agent such as lead dioxide.If the electrolyte contains a surfactant consisting of perfluoroalkylamine oxide, it will react with lead sulfate. Lowers the interfacial tension of the electrolyte,
The electrolytic solution enters between the crystals of lead sulfate, which has poor wettability as it is, reducing the current density during charging and improving charge acceptance after being left overdischarged.

With these configurations, the present invention lowers the interfacial tension between the electrolyte and lead sulfate by including a perfluoroalkylamine oxide surfactant in the lead-acid battery.

That is, by this effect, it is possible to improve the charge acceptance of the lead-acid battery after it is left over-discharged. Therefore, even in a battery that has been left over-discharged, charging can be completed in the same charging time as immediately after discharging.

Example Examples of the present invention will be described below.

A sealed lead-acid battery with a voltage of 12 V and a 10 hour rate capacity of 2▲b was created by combining positive and negative electrode plates and a separator made of fine glass fiber. Dilute sulfuric acid with a specific gravity of 1.32 was used as the electrolyte. C, F, 1CONH (CH2),
H''(CH3)3I was added to the electrolyte as a surfactant at 1×1''0-5, 1X10''-'1X10, 1, respectively.
×10, and o. swt% was added. I tried to add IWt%, but it did not dissolve.

The charge acceptability after overdischarging was tested using the thus prepared battery and, for comparison, a battery prepared without adding a surfactant. First, a test was conducted after fully charging at 0.1 C▲, but the test was canceled because bubbles overflowed from the exhaust port with the one containing o-swt%.

A constant resistance discharge equivalent to 0.76 people was performed for 24 hours at 25°C with other items, and then left at 25°C for one month.
14.8V/1. The rush current when charging using the constant voltage constant current method of e▲ and the time it takes to reach 1.6▲ are the first
Shown in the figure. In this figure, those located further to the lower right have better charge acceptance.

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

Figure 1. As is clear from FIG. 2, the inrush current increases due to the addition of both, and the time required to reach 1.6 people becomes shorter. The faster the inrush current reaches <1.6▲, the larger the amount of electricity charged. 3rd e e Figure 1cc,F,,COMM(OH2)3N (CH3)
The graph shows the change in current during constant voltage charging for the case with 1×1 wt% of 3I added and the case without addition.

In addition, if the amount added is small, the effect will not be seen, and even if perfluoroalkylamine oxide is relatively soluble in sulfuric acid, if the amount added is increased, it will form when gas is generated during charging. This is not desirable because the bubbles will not disappear and will overflow from the exhaust port.

Effects of the Invention As described above, according to the present invention, it is possible to provide a lead-acid battery with improved charge acceptance after being left over-discharged.

[Brief explanation of drawings]

Figure 1 shows the relationship between the inrush current and the time until the maximum current is reached after overdischarging, Figure 2 shows the relationship between the amount of surfactant added and the amount of electricity charged, and Figure 3 shows the relationship between the amount of surfactant added and the amount of electricity charged. FIG. 4 is a current characteristic diagram during constant voltage charging. Name of agent: Patent attorney Shigetaka Awano and one other person Figure 9 of amf no LX4L!入j”rt (m.4 冫MIN role Keyaki w Biao N,i

Claims (2)

[Claims] (1) Lead dioxide as the positive electrode active material, spongy lead as the negative electrode active material,
In lead-acid batteries that use dilute sulfuric acid as the electrolyte, C
_nF_2_n_+_1CONH(CH_2)_3N^
■A lead-acid battery characterized by the presence of a perfluoroalkylamine oxide surfactant represented by (CH_3)_3I^■. (2) The lead-acid battery according to claim 1, wherein 4 x 10^-^4 to 1 x 10^-^2 wt% of perfluoroalkylamine oxide is added to the electrolyte.