JPH09330732A - Lead-acid battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the reduction in hydrogen over-voltage of a negative electrode and improve the voltage characteristic by adding a prescribed % of sodium silicate to a diluted sulfuric acid electrolyte. SOLUTION: A positive electrode plate formed of a grid base consisting of a Pb-Sb alloy and an active material paste consisting of lead powder and diluted sulfuric acid which is filled therein, and a negative electrode plate form of a grid base consisting of a Pb-Ca alloy and an active material paste formed of lead oxide and diluted sulfuric acid which is filled therein are formed. A number of batteries having a 5-hour rate capacity of 48 Ah which contains an electrode group formed of these negative and positive electrode plates and a separator interposed between them and 3.9l of a diluted sulfuric acid electrolyte having a specific gravity at 20 deg.C of 1.280 are manufactured. In the manufacture of each electrolyte, 0.08-3.82wt.% of sodium silicate is added and dissolved to the diluted sulfuric acid electrolyte as capturing agent. At a result of charge and discharge cycle tests for these batteries, 0.9-4.0wt.% of sodium silicate is added to the diluted sulfuric acid electrolyte, whereby the metal ion eluted from the positive electrode is prevented from being deposited on the negative electrode to provide an effect of improvement in starting voltage of the battery.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead storage battery used in automobiles and the like.

[0002]

2. Description of the Related Art Conventionally, Pb is mainly used and a small amount of S is added to it.
An anode plate made by adding an active material paste made by adding dilute sulfuric acid to lead powder and well kneading the mixture to a lead alloy substrate made of Pb-Sb made by adding a metal such as b, drying, and forming. Pb-
A cathode plate made by adding lead oxide such as Ca to a lead alloy substrate with dilute sulfuric acid and thoroughly kneading the mixture, drying and forming a cathode plate was interposed between these cathode and anode plates. A lead acid battery having a built-in electrode group consisting of a separator and a dilute sulfuric acid electrolyte is known.

[0003]

SUMMARY OF THE INVENTION The lead-acid battery described above has Pb-Sb of the positive electrode as the charging / discharging cycle progresses.
However, there has been a problem that the added metal in the lead alloy substrate made of various alloys and other alloys is eluted as metal ions into the sulfuric acid electrolyte and deposited on the cathode plate to lower the hydrogen overvoltage. In order to prevent such inconvenience, it is known to add a scavenger that traps antimony ions flowing out from a Pb-Sb-based lead alloy anode plate to a sulfuric acid electrolytic solution or the like to prevent precipitation on the negative electrode. . The present invention aims at finding a novel scavenger different from the above-mentioned known scavengers, and thereby eliminating the above-mentioned inconvenience.

[0004]

SUMMARY OF THE INVENTION The present invention provides a lead-acid battery that solves the above-mentioned problems, in which sodium silicate is added in an amount of 0.9 to 4.0 wt. %.

[0005]

Next, an embodiment of the present invention will be described. A grid substrate made of a Pb-Sb alloy, lead powder mixed with dilute sulfuric acid and well kneaded, filled with an active material paste, dried and formed into an anode plate, and a Pb-Ca alloy. Dilute sulfuric acid is added to lead oxide on a grid substrate, well kneaded, filled with an active material paste, dried, and formed into a cathode plate, and a polyolefin separator and a glass mat are laminated between the cathode and anode plates. A large number of lead acid batteries for automobiles having a 5-hour rate capacity of 48 Ah, in which an electrode plate group including the above-mentioned elements and a 3.9 liters of a dilute sulfuric acid electrolytic solution having a specific gravity of 1.280 at 20 ° C. are built, are manufactured. In this case, as the respective electrolytic solutions, 0.08 M / l, 0.1 M / l, 0.2 M / l of sodium silicate (Na ₂ SiO ₃ , molecular weight 122 g) as a scavenger was added to the diluted sulfuric acid electrolytic solution. And 0.
A device containing the electrolytic solution of the present invention in which 4 M / l was added and dissolved was prepared. The concentration of sodium silicate with respect to the diluted sulfuric acid electrolyte solution, 0.08 M / l, 0.1 M / l, 0.2 M / l and 0.4 M / l, is 0.080% by weight of sodium silicate (39.9 g), respectively. , 0.95% by weight (47.6 g),
1.91 wt% (95.2 g), 3.82 wt% (19
0.3 g), respectively.

[0006] Thus, the following charge / discharge cycle test was conducted for each lead storage battery with different addition amount of sodium silicate and no addition storage battery. That is, a light load life test at 75 ° C. was carried out as the charge / discharge cycle progressed, and the cycle life, the liquid reduction amount, and the end-of-charge current were examined. Light load life test is S except for ambient temperature 75 ℃.
Based on BA (Japan storage battery industry standard), charging is performed at 14.8 ± 0.03V (limited current 25A) for 10 minutes, discharging is performed at 25 ± 0.05A for 4 minutes. It is set as 1 time and left for 480 times for 56 hours, after which it is discharged for 30 seconds at the judgment current of 356 A, and the voltage at the 30th second becomes 7.2 V, and it is judged as the life when the voltage does not rise again. The number of charge / discharge cycles up to the point of time is taken as the life of the battery, but in the case of the present invention, in consideration of the use environment of the automobile battery, the ambient temperature of the SBA standard is changed to 40 to 45 ° C. Was placed in a constant temperature bath of 75 ° C., and the above-mentioned light load life test was performed under an ambient environment of 75 ° C. Also, in this charge / discharge cycle test,
The amount of electrolyte reduction and the end-of-charge current were determined with the progress of the charge / discharge cycle. The results are shown in FIG.
1B and 1C, respectively.

As is clear from the comparative graphs shown in FIGS. 1 (a) to 1 (c), the cycle life of the battery is improved and decreased when sodium silicate is added, as compared with the case where no sodium silicate is added. Although the liquid amount is small and the end-of-charge current is small, the addition effect is recognized. The addition effect is that the addition amount is 0.80 wt. %, There is almost no difference from the case of no addition and there is only a slight addition effect, but the addition amount is 0.95.
wt. % Or more to 3.82 wt. It can be seen that a significant addition effect can be obtained with%. As a result of many tests, the addition amount was 0.9 wt. % Or more 4 wt. % Is preferred, 4w
t. If it exceeds%, it becomes saturated and cannot be completely dissolved in the electrolytic solution, and the effect is the same. Therefore, any further addition is uneconomical.

Furthermore, the presence or absence of adverse effects due to the addition of sodium silicate in these batteries was compared by measuring the 5-hour capacity immediately after the addition. The results are shown in Table 1 below.

[0009]

[Table 1]

In Table 1, the numerical value in parentheses is a comparison value when the measured value without addition is 100. Table 1 above
As is clear from 0.9 wt. %, No adverse effect was observed.

Further, these batteries were tested in the following manner, and the effect of addition after standing for over discharge was examined. Each of these batteries was tested as follows, before being left over-discharged.
An overcharge current value of 14.2 V at ℃ was measured. That is, first, (a) each battery is charged according to JIS 5301 with a discharge current of a 5-hour rate capacity, the voltage is measured every 15 minutes, and the measurement is performed three times in succession to a fully charged state showing a constant value. Then, put it in a constant temperature water bath at 75 ° C and let the battery reach 75 ° C.
The charging current value when the constant voltage charging of 4.2V was performed was measured. Next, (b) each of these batteries was discharged at a rate of 5 hours and then allowed to stand for over discharge at 40 ° C. for 30 days, and then tested in the same manner as in (a) above, and the charging current value was measured. The results are shown in Table 2 below.

[0012]

[Table 2]

In Table 2 above, the values in parentheses are comparison values when the measured value without addition is 100. As is clear from Table 2, 0.95 wt. When the amount added is at least%, the value of the overcharge current becomes extremely remarkably smaller than that of the non-added battery even after the battery is left overdischarged. This significantly prevents the metal ions such as antimony eluted in the electrolytic solution from the positive electrode lead alloy grid from depositing on the cathode at such an added amount, thus preventing the hydrogen overvoltage of the negative electrode from being lowered and reducing the battery It can be seen that the electromotive voltage is improved. In other words, lead-acid batteries for automobiles generally perform constant voltage charging, so when the battery voltage drops, it becomes difficult to reach the set voltage, and the charging current value increases and overcharging occurs, but this has the effect of being prevented. .

In the above embodiment, the substrate made of Pb-Sb alloy was used as the lead alloy substrate for the anode, but it may be made of lead alloy such as Pb-Sn or Pb-Ca instead. . Further, the lead specification battery is not limited to the hybrid specification.

[0015]

As described above, according to the present invention, 0.9 to 4.0 wt. % Of sodium silicate, the metal ions eluted from the anode are trapped and prevented from being deposited on the cathode, so that the hydrogen overvoltage of the cathode is prevented from lowering and the voltage characteristics are improved.

[Brief description of drawings]

FIG. 1 (a) is a comparative graph showing the relationship between the amount of sodium silicate added to a dilute sulfuric acid electrolytic solution and the battery life.

FIG. 1 (b) is a comparative graph showing the relationship between the amount of sodium silicate added and the liquid reduction with the progress of charge / discharge cycles.

FIG. 1 (c) is a comparative graph showing the relationship between the amount of sodium silicate added and the end-of-charge current of the battery.

Claims (1)

[Claims] 1. A dilute sulfuric acid electrolytic solution containing 0.9% sodium silicate.
~ 4.0 wt. % Lead-acid battery.