JP3008564B2 - Lead storage 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 lead-acid battery, and more particularly, to a lead-acid battery in which a negative electrode grid and a negative electrode strap are composed of alloys having different compositions.

[0002]

2. Description of the Related Art Conventionally, the electrodes of lead-acid batteries are generally formed of a lead-antimony alloy. However, in recent years, in order to improve the corrosion resistance of this electrode grid, antimony is not used in the electrode grid alloy at all and calcium is used. A lead-acid battery (hereinafter, referred to as a calcium battery) using Pb and a lead-acid battery (hereinafter, referred to as a hybrid battery) in which only the positive electrode grid contains antimony and the negative electrode grid does not contain antimony have been developed. Generally, a lead alloy containing calcium is used for a negative electrode lattice of this type of battery, and a lead alloy containing antimony is used for a negative electrode strap. That is, in a calcium battery or a hybrid battery, the negative electrode is composed of a negative electrode lattice and a negative electrode strap having different alloy compositions. In this type of battery, the corrosion resistance of the grid itself is improved, and antimony is not used for the positive electrode. Therefore, the suppression of electrolyte reduction is significantly improved. It has been put to practical use as a so-called maintenance-free lead storage battery.

[0003]

However, the operating environment of recent lead-acid batteries is increasing year by year. For example, in the case of lead-acid batteries for automobiles, the use environment of lead-acid batteries is becoming higher and higher due to an increase in engine displacement, a compact engine room design for expanding living space, traffic congestion, and the like. Thereby, for example, even in the case of a hybrid battery, compared to a conventional use environment,
As the overcharge current increases and the grid corrodes, antimony in the positive grid dissolves and precipitates on the negative plate surface,
The liquid reduction suppressing property gradually deteriorates during use, and the liquid electrolyte is reduced. By the way, in a lead storage battery, the highest liquid level line and the lowest liquid level line are displayed outside the battery. Of these, the lowest liquid level line is generally used for the purpose of increasing the amount of electrolyte reaching water replenishment. At the upper end of the electrode plate group. In such a configuration, when the electrolyte is reduced to the lowest liquid level line , the contact point between the negative electrode grid and the strap, that is, the contact point between the dissimilar metals, is exposed. It has been found that significant corrosion occurs in the contact area. Such a problem does not occur when the entire negative electrode is formed of one type of alloy as in the related art. That is, the phenomenon of corrosion of the contact portion between the negative electrode grid and the negative electrode strap is a new problem caused by joining dissimilar metals. In order to suppress this corrosion, studies are being made on welding conditions and the like, but the corrosion rate can be reduced, but no fundamental measures have been taken.

Accordingly, an object of the present invention is to provide a lead-acid battery capable of almost completely preventing the above-described corrosion of a negative electrode in which a lattice and a strap are made of dissimilar metals.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a lead-calcium alloy.
From negative electrode grid made of aluminum alloy and lead-antimony alloy
In lead-acid battery comprising a negative electrode strap made, a minimum fluid lines to indicate the lowest level of the electrolyte, the lead - calcium
And a lead-antimony-based alloy disposed above a portion where the alloy contacts.

The inventors of the present invention have conducted intensive studies on corrosion at different metal contact points when the negative electrode grid and the negative electrode strap are made of alloys having different compositions. It was found that the corrosion did not occur at all unless it was exposed.

[0007] The present invention is based on this finding,
In a storage battery in which the negative electrode grid and the negative electrode strap are made of alloys having different compositions, the lowest liquid level line indicating the lowest level of the electrolytic solution is arranged above a place where the dissimilar alloy contacts. is there.

[0008]

The lead storage battery may be provided with an indicator for indicating the amount of the electrolytic solution. In this case, the operating position of the indicator is equal to or higher than the contact point between the dissimilar metals, that is, the minimum liquid level line. It is desirable to make it.

Furthermore, a so-called OK monitor can be installed, and the operating position of the OK monitor can be made to coincide with the contact point of the dissimilar metal or more, that is, with the minimum liquid level line.

[0011]

[Action] The mechanism by which the contact portion of the dissimilar metal corrodes is
Although not completely elucidated, the spontaneous potential is slightly different due to dissimilar metals, forming a local battery near the contact part,
Furthermore, it is considered that corrosion occurs due to the involvement of oxygen in the air.However, as in the present invention, if the contact portion of the dissimilar metal of the negative electrode is always exposed to the liquid surface of the electrolytic solution or less,
No corrosion occurs at the contact points.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a lead-acid battery according to a preferred embodiment of the present invention. In this embodiment, the lead storage battery will be described as a so-called hybrid battery.

FIG. 1 is a partially cutaway front view of a lead storage battery according to an embodiment of the present invention. In this figure, reference numeral 1 denotes a battery case. Inside the battery case 1, a positive electrode (not shown) and a negative electrode 2 are arranged as in a normal hybrid battery. This negative electrode 2 has an electrode lug 4 on the upper part, and connects a large number of negative plates 3 having a lattice formed of a lead-calcium alloy and the electrode lugs 4 of these negative plates 3. And a strap 5 formed of a lead-antimony alloy. A free electrolytic solution is stored in the battery case 1. A maximum liquid level line (not shown) for indicating the highest level of the electrolytic solution and a minimum level are provided outside the battery case 1. A minimum liquid level line 6 is provided for indicating.
The minimum liquid level line 6 is used to indicate that water replenishment should be performed before the liquid level of the electrolytic solution falls below this line.
It is set above the contact point between the dissimilar metals which are a calcium alloy and a lead-antimony alloy. This allows
The contact points of the dissimilar metals are not exposed at any time to prevent corrosion at these points.

In the hybrid battery having the above configuration,
A corrosion test was performed. The positive electrode was formed of a lead-antimony alloy in the same manner as a normal one.

In this test, a constant voltage overcharge test (charging voltage: 14.0 V) was performed on the battery in an atmosphere of 60 ° C.
Was done. Water replenishment was performed when the electrolyte reached the minimum liquid level line.

After the test was conducted for 20 weeks, the battery was disassembled and the state of corrosion of the negative electrode was examined.

As a comparative example, a battery having the same configuration as that of the above embodiment was prepared except that the lowest liquid level line was set at the upper end of the electrode plate, and a constant voltage overcharge test was performed under the same conditions.
In the battery of this comparative example, the ears of all the electrodes were disconnected due to corrosion.

[0018]

[0019]

As described above, the present invention has an extremely high effect of preventing disconnection due to corrosion of the negative electrode ear.

For example, as shown in FIG. 2, a columnar prism 10 made of a transparent acrylic resin or the like is installed on a lid (not shown) of the battery case 1 and the lower end thereof is just set to the lowest liquid level line. 6 (the extension line of the lowest liquid level line is indicated by an imaginary line), if the lower end of the prism floats due to the lowering of the liquid level, the action of the prism causes
The state changes from the transmission state to the reflection state, and the liquid level can be easily reduced to a level lower than the minimum liquid level line. Also, as shown in FIG.
A so-called OK monitor 20 may be provided to positively notify the lowering of the liquid level below the minimum liquid level line by a buzzer or the like. In this OK monitor, for example, a pair of detection electrodes 21 is attached to a lid of a battery case, and is installed such that the lower ends thereof are exactly at the position of the lowest liquid level line 6 (an extension of the lowest liquid level line is indicated by an imaginary line). If the detection electrode is immersed in the electrolyte,
When the signal output is off and the liquid level drops and the detection electrode is exposed from the liquid, the signal output is turned on to signal a drop in the liquid level.

[0022]

As described above, the lead storage battery of the present invention can effectively prevent the corrosion of the joint between the negative electrode lug and the negative electrode strap, that is, the contact of the dissimilar metal, which proceeds by being exposed from the electrolytic solution. Thus, a highly safe battery can be obtained.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view of a lead storage battery according to an embodiment of the present invention.

FIG. 2 is a partially cutaway front view of a lead-acid battery according to another embodiment of the present invention.

FIG. 3 is a partially cutaway front view of a lead storage battery according to still another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Battery case 2 Negative electrode 3 Negative electrode plate 4 Electrode ear part 5 Strap 6 Minimum liquid level line 10 Prism 11 OK monitor

Continuation of the front page (56) References JP-A-63-226876 (JP, A) JP-A-1-225071 (JP, A) JP-A-63-149067 (JP, U) JP-A-63-82378 (JP) , U) (58) Fields surveyed (Int. Cl. ⁷ , DB name) H01M 10/06, 10/12, 10/48

Claims (2)

(57) [Claims] A negative electrode grid made of a lead-calcium alloy ;
In a lead-acid battery provided with a negative electrode strap made of a lead-antimony alloy, a minimum liquid level line indicating the minimum level of the electrolyte is drawn by the lead-calcium alloy and the lead-antimony.
A lead-acid battery, wherein the lead-acid battery is disposed above a location where the mon-based alloy contacts. 2. The lead-calcium alloy and the lead-an alloy.
2. The lead-acid battery according to claim 1, wherein a mutual melting and mixing layer of each alloy is formed at a contact portion of the thymon-based alloy .