JP3489361B2 - Sealed lead-acid battery - Google Patents

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In recent years, with the widespread use of electric vehicles and electric lawn mowers, there is a demand for high reliability and extended battery life of sealed lead-acid batteries incorporated in these devices for vehicle applications.

In a conventional sealed lead-acid battery, a separator holds an electrolytic solution, and a gas generated from a positive electrode plate during charging is absorbed by a negative electrode plate to maintain hermeticity. FIG. 4 is a schematic cross-sectional view of a main part of a conventional sealed lead-acid battery in which an electrode plate group is inserted in a battery case. In FIG. 4, 1 is a positive electrode plate, 2 is a negative electrode plate, 3 is a separator, and 4 is a battery case. When the sealed lead-acid battery configured in this way is used in a stationary state, it can be sufficiently charged and discharged repeatedly,
If the battery is vibrated when it is handled, the battery capacity often decreases early. In this case, most of the capacity deterioration is due to the softening of the positive electrode plate. As a method of considering this type of vibration resistance, JP-A-55-1311
There is a method of forming a synthetic resin for fixing an electrode plate by mixing a curing agent in which an epoxy resin and a fine silicic acid powder are mixed, as disclosed in Japanese Patent No. However, by fixing the electrode plate group, the resin penetrates into the active material under the electrode plate and cannot contribute to the discharge reaction, so that a sufficient battery capacity cannot be maintained.

[0004]

In the conventional sealed lead-acid battery, when the battery is vibrated during handling, the capacity of the battery decreases early. It was caused by the deviation in the direction of large vibration inside and a gap between the inner wall of the battery case and the electrode plate group. That is, when the battery is used in a state where the electrode plates in the battery case are offset, the gas generated during charging tends to accumulate in this gap.
This phenomenon is due to the fact that the negative electrode plate facing the outermost gap of the electrode plate group absorbs a larger amount of gas in comparison with other negative electrode plates in the gas absorption reaction. As a result, a large amount of current flows through the positive electrode plate facing the negative electrode plate, and the electrode plate becomes the most burdened electrode plate in this electrode plate group and deteriorates quickly, resulting in a problem in the battery itself. It was

Therefore, the present invention is intended to provide a sealed lead-acid battery in which the capacity of the battery does not decrease early even if vibration is applied during handling of the battery.

[0006]

In order to solve the above-mentioned problems, according to the present invention, in a sealed lead-acid battery, 20 to 30% of the total height of the reaction area of the electrode plate from the bottom of the electrode plate group is stored in a battery case. Gelling an aqueous solution of alkali silicate and dilute sulfuric acid
It is fixed by doing so , and the electrode plate group is arranged so as not to move to a predetermined position. Even if vibration is applied during handling, the vibration does not create a gap between the electrode plates and the inner wall of the battery, and some of the plates in the electrode plate are biased. This prevents early deterioration of the electrode plate. This makes it possible to secure the battery capacity and extend the cycle life when the battery is vibrated.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In a state where an electrode plate group composed of a positive electrode plate, a negative electrode plate and a separator is housed in a battery case, the total height of the electrode plate reaction area is measured from the bottom of the electrode plate group. 20
~ 30% of alkali silicate such as sodium silicate and dilute sulfuric acid
The mixed aqueous solution is gelled and fixed in a battery case . By taking this measure, the position of the electrode plate group in the battery case will be properly arranged, and if vibration is applied while the battery is in use, the vibration will cause a gap between the electrode plate group and the inner wall of the battery case. It is possible to suppress the early deterioration of the electrode plates due to the fact that a part of the electrode plates in the electrode plate group is biased and the load is applied to the electrode plates without causing the occurrence of.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

The sealed lead-acid battery of the present invention is as shown in FIG.
Sodium silicate is mixed in the electrolytic solution and injected into each cell.The electrode group is inserted into the battery cell and then allowed to stand or dry to gelate the electrolytic solution and charge the electrode group. Fix in the bath. In FIG. 1, 1 is a positive electrode plate, 2 is a negative electrode plate, 3 is a separator, 4 is a battery case, and 5 is a portion fixed by a gelled electrolytic solution .

The sodium silicate (Na ₂ O.nSiO ₂ .mH ₂ O) used in the sealed lead acid battery of the present invention contains 20 Na ₂ O.
~ 21 wt%, SiO ₂ 0.95 wt% or less, H ₂ O
Was 79 to 80% by weight. The lower part of the electrode group was immersed in an aqueous solution obtained by mixing this sodium silicate and dilute sulfuric acid. The immersion range is from the bottom of the electrode plate group to the total height of the electrode plate reaction area of 10
%, 20%, 30% and 35%, and dilute sulfuric acid was further added so that the same immersion range was obtained, and a battery was prepared in which the electrode plate group was inserted into the battery case. Using 12V65Ah battery, trial evaluation was carried out on a total of 5 types of sealed lead acid batteries in which the 4 types of batteries and the current electrode group that was not immersed in the sodium silicate aqueous solution were inserted into the battery case.

Of the five prototype batteries, the total height of the reaction area of the electrode plate was 35 from the bottom of the electrode plate group to the aqueous solution of sodium silicate.
%, The electrolyte solution penetrated into the electrode active material and could not be gelled. Therefore, the immersion of the electrode plate group was set to 10%, 20%, and 30% described above, and the batteries prepared by the current electrode plate group were designated as A, B, C, and D, respectively.

The evaluation was carried out by mounting six prototype batteries of four kinds of A, B, C, and D batteries on each electric tricycle as shown in FIG. 2 in which two batteries were used in series. Take an electric tricycle equipped with A, B, C, and D batteries respectively, and run a course with a running distance of 12 km with vibration and undulation (average current value during running 6.5 A, running time about 2 hours), then The battery was charged with a constant current so that 120% of the amount of electricity discharged was contained. This test was conducted once a day on electric tricycles equipped with A, B, C, and D batteries, and this was set as one cycle, and the battery was taken out from the electric tricycle every 20 cycles and the capacity was confirmed.

The capacity was confirmed by discharging 0.1 CA (final voltage 1.75 V / cell) and 2.45 V / cell (0.4
After charging for 24 hours at (CAmax), the vehicle returned to the running test with the electric tricycle. When confirming the capacity, when the capacity reached 50% of the initial capacity, the life was judged to have ended, and the test was terminated. In such a test, 400 cycles or more was set as a standard for a long-life battery.

The test results are shown in FIG. The electric tricycle equipped with the battery of D had a result that the running became insufficient before 300 cycles were reached, and as a result of checking the battery capacity, the capacity decreased. On the other hand, the A, B, C batteries are 4
The capacity was maintained even after 00 cycles had passed. 500
At the time when the cycle passed, all tests were completed and the battery was analyzed. From the battery disassembly investigation, in the battery of D, the electrode plate group was biased to the side where the vibration applied to the battery in the battery case is large as shown in FIG. It was The deterioration of the negative electrode plate in contact with the gap and the deterioration of the active material of the positive electrode plate facing the negative electrode plate were remarkable.

As described above, when the electrode plate group in the battery case charges the battery in such a state, the gas generated at the time of charging easily passes through this gap, and the gas absorption At this time, the negative electrode plate located on the outermost side of the electrode plate group and facing the gap absorbs a large amount of gas as compared with other negative electrode plates. As a result, a large amount of current flows in the positive electrode plate facing the closest to this negative electrode plate, becoming the most burdensome electrode plate in this electrode plate group, and deteriorates early, resulting in a decrease in the capacity of the battery itself. It became clear.

The battery of A began to deteriorate after reaching 400 cycles. From the results of the disassembly examination, it was confirmed that there was a gap between the inner wall of the battery case and the electrode plate group, although it was smaller than the D battery. Since the fixing range is small when the range immersed in the sodium silicate aqueous solution is about 10%, a gap gradually occurs between the electrode plate group and the inner wall of the battery case due to the vibration during the running until the latter half of the cycle test, and the electrode plate. It was not effective enough to immobilize the group and the inner wall of the battery case.

Regarding the batteries B and C, no tendency of early deterioration was observed and the battery capacity could be maintained at 500 cycles. From the results of the disassembly investigation, the electrode plate group was firmly fixed in the battery case in the same state as before the test as shown in Fig. 1, there were no gaps, and the electrode plates reacted uniformly and deteriorated due to deviation. Was not seen. From the above, it was shown that the present invention has a remarkable effect in cycle use when vibration is applied during handling of the battery.

It is effective to set the range of immobilization from the bottom of the electrode plate group to 20 to 30% of the total height of the reaction area of the electrode plate.

Further, although sodium silicate is used in this embodiment, an alkali silicate, which is a substance that can be gelled and similarly fixed, can be fixed in the same manner as sodium silicate.

[0020]

As described above, by gelling with an alkali silicate and fixing the bottom of the electrode plate group with the inner wall of the battery case, the cycle life characteristics in use where vibration is applied can be improved, and reliability is improved. It is possible to supply a highly sealed sealed lead acid battery.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a main part of a sealed lead-acid battery when an electrode plate group according to an embodiment of the present invention is inserted in a battery case.

FIG. 2 is a perspective view of an electric tricycle equipped with the sealed lead-acid battery.

FIG. 3 is a curve diagram showing cycle characteristics of the sealed lead acid battery shown in the embodiment of the present invention and a conventional sealed lead acid battery.

FIG. 4 is a cross-sectional view of a main part of a conventional sealed lead-acid battery when the electrode plate group is inserted in a battery case in the conventional sealed lead-acid battery.

FIG. 5 is a cross-sectional view of essential parts showing a state where the electrode plate group is inserted into the battery case when the sealed lead-acid battery is vibrated.

[Explanation of symbols]

1 Positive plate 2 Negative electrode plate 3 separator 4 battery case 5 fixed part

Claims (2)

(57) [Claims] 1. An alkali silicate and dilute sulfuric acid are mixed in a battery case in an amount of 20 to 30% of the total height of the reaction area of an electrode plate from the bottom of an electrode plate group composed of a positive electrode plate, a negative electrode plate and a separator.
A sealed lead acid battery characterized in that it is immobilized by gelling the combined aqueous solution . 2. The sealed lead storage battery according to claim 1, wherein the alkali silicate is sodium silicate.